1000 or one thousand is the natural number following 999 and preceding 1001. In most English-speaking countries, it can be written with or without a comma or sometimes a period separating the thousands digit: 1,000.
A group of one thousand units is sometimes known, from Ancient Greek, as a chiliad. A period of one thousand years may be known as a chiliad or, more often from Latin, as a millennium. The number 1000 is also sometimes described as a short thousand in medieval contexts where it is necessary to distinguish the Germanic concept of 1200 as a long thousand. It is the first 4-digit integer.
Contents
Notation
The decimal representation for one thousand is
1000—a one followed by three zeros, in the general notation;
1 × 103—in engineering notation, which for this number coincides with:
1 × 103 exactly—in scientific normalized exponential notation;
1 E+3 exactly—in scientific E notation.
The SI prefix for a thousand units is "kilo-", abbreviated to "k"—for instance, a kilogram or "kg" is a thousand grams. This is sometimes extended to non-SI contexts, such as "ka" (kiloannum) being used as a shorthand for periods of 1000 years. In computer science, however, "kilo-" is used more loosely to mean 2 to the 10th power (1024 or 210).
In the SI writing style, a non-breaking space can be used as a thousands separator, i.e., to separate the digits of a number at every power of 1000.
Multiples of thousands are occasionally represented by replacing their last three zeros with the letter "K" or "k": for instance, writing "$30k" for $30,000 or using "Y2K" to denote the Year 2000 computer problem.
A thousand units of currency, especially dollars or pounds, are colloquially called a grand. In the United States, this is sometimes abbreviated with a "G" suffix.
In mathematics
A chiliagon is a 1000-sided polygon.
Numbers in the range 1001–1999
1001 to 1099
1004 = 22 × 251. It is a heptanacci number.
1009 is the smallest four-digit prime, a Lucky prime, and Chen prime. It is palindromic in bases 11, 15, 19, 24 and 28: (83811, 47415, 2F219, 1I124, 18128).
1011 = 3 × 337. It is a Harshad number in bases 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 (and 202 other bases). It is the largest natural number n such that 2n contains 101 and does not contain 11011. There are 1011 partitions of 1 into reciprocals of positive integers <= 16 Egyptian fraction.
1013 is a prime number, a Sophie Germain prime, and a centered square number,
1016 = 23 × 127. It is stella octangula number and a member of the Mian–Chowla sequence. There are 1016 surface points on a cube with edge-length 14.
1019 is a Sophie Germain prime, a safe prime, and a Chen prime.
1021 is a Lucky prime and a twin prime with 1019.
1025 = 52 × 41. It is a Jacobsthal-Lucas number and the hypotenuse of a primitive Pythagorean triangle. It is a Proth number because 1025 = 210 + 1. It is a member of the Moser–de Bruijn sequence because its base-4 representation (1000014) contains only digits 0 and 1, or equivalently, it's a sum of distinct powers of 4 (45 + 40).
1028 = 22 × 257. It is sum of totient function for first 58 integers.
There are 1029 primes <= 213.
1031 is a prime number, a Sophie Germain prime, a super-prime, and a Chen prime. It is the exponent and number of ones for the fifth base-10 repunit prime.
1033 is a prime number and an emirp. It forms a twin prime pair with 1031.
1100 to 1199
1102 = 2 × 19 × 29. It is the sum of the totient function for the first 60 integers.
1103 is a prime number, a Sophie Germain prime, and a balanced prime.
1104 = 24 × 3 × 23. It is a Keith number
1109 is a Chen prime.
1113 = 3 × 7 × 53. There are 1113 strict partions of 40.
1117 is a Chen prime. There are 1117 diagonally symmetric polyominoes with 16 cells.
1118 = 2 × 13 × 43. There are 1118 unimodular 2 × 2 matrices having all terms in {0,1,...,21}.
1119 = 3 × 373. There are 1119 bipartite graphs with 9 nodes.
1122 = 2 × 3 × 11 × 17. It is a pronic number.
1123 is a balanced prime.
1126 = 2 × 563. There are 1126 2 × 2 non-singular integer matrices with entries from {0, 1, 2, 3, 4, 5}.
1127 = 72 × 23. It is the maximum number of pieces that can be obtained by cutting an annulus with 46 cuts.
1128 = 23 × 3 × 47. It is the 47th triangular number and the 24th hexagonal number. 1128 is the dimensional representation of the largest vertex operator algebra with central charge of 24, D24.
1151 is the first prime number following a prime gap of 22. It is also a Chen prime.
1152 = 27 × 32. It is a highly totient number, a 3-smooth number, and an Achilles number.
1200 to 1299
1200 = 24 × 3 × 52. There are 1200 households in the Nielsen ratings sample.
1200 is known as the long thousand or ten "long hundreds" of 120 each. It is the traditional reckoning of large numbers in Germanic languages.
1201 is a super-prime, a centered square number, and a centered decagonal number.
1202 = 2 × 601. There are a maximum of 1202 regions when the plane is divided by 25 ellipses.
1203 = 3 × 401. It is the smallest number greater than 1000 in the coordinating sequence for the (2,6,∞) tiling of the hyperbolic plane.
1204 = 22 × 7 × 43. It is the magic constant for a 7 × 7 × 7 magic cube.
1205 = 5 × 241. There are 1205 partitions of 28 such that the number of odd parts is a part
1207 = 17 × 71. It is a composite de Polignac number.
1208 = 23 × 151. There are 1208 strict chains of divisors starting with the superprimorial A006939(3).
1210 = 2 × 5 × 112. It is an amicable number with 1184 and a Self-descriptive number.
1211 = 7 × 173. It is a composite de Polignac number
1212 = 22 × 3 × 101 =
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k
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0
1300 to 1399
1300 = 22 × 52 × 13. It is a zero of Mertens function and the smallest even odd-factor hyperperfect number. It is the sum of the first 4 fifth powers:
1300 = 15 + 25 + 35 + 45.
1301 is a prime number and a centered square number. There are 1301 trees with 13 unlabeled nodes.
1306 = 2 × 653. It is a centered triangular number.
1307 is a safe prime.
1308 = 22 × 3 × 109. It is the sum of the totient function for the first 65 integers.
1312 = 25 × 41. It is a member of the Mian-Chowla sequence.
1319 is a safe prime.
1325 = 52 × 53. It is a Markov number and a centered tetrahedral number.
1326 = 2 × 3 × 13 × 17. It is the 51st triangular number and a hexagonal number.
1327 is the smallest prime number preceding a prime gap of 34.
1328 = 24 × 83. It is the sum of the totient function for the first 66 integers.
1330 = 2 × 5 × 7 × 19. It is a tetrahedral number. It forms a Ruth–Aaron pair with 1331 under second definition.
1331 = 113. It is a centered heptagonal number. It forms a Ruth–Aaron pair with 1330 under second definition.
1335 = 3 × 5 × 89. It is a pentagonal number.
1400 to 1499
1403 = 23 × 61. It is the smallest number x such that M(x) = 11, where M() is Mertens function
1404 = 22 × 32 × 13. It is a heptagonal number.
1405 = 5 × 281 = 262 + 272 = 72 + 82 + ... + 162. It is a centered square number
1406 = 2 × 19 × 37. It is a semi-meandric number.
1409 is a super-prime, a Sophie Germain prime, and a Proth prime.
1410 = 2 × 3 × 5 × 47. It is the denominator of the 46th Bernoulli number
1418 = 2 × 709. It is the smallest number x such that M(x) = 13, where M() is Mertens function
1425 = 3 × 52 × 19. It is a self-descriptive number in base 5.
1426 = 2 × 23 × 31. It is a pentagonal number and the sum of the totient function for the first 68 integers. There are 1426 strict partions of 42.
1427 is a twin prime with 1429.
1428 = 22 × 3 × 7 × 17. There are 1428 complete ternary trees with 6 internal nodes or, equivalently, 18 edges.
1429 is a twin prime with 1427.
1430 = 2 × 5 × 11 × 13. It is a Catalan number.
1431 = 33 × 53. It is the 53rd triangular number and a hexagonal number.
1432 = 23 × 179. It is a member of the Padovan sequence.
1500 to 1599
1500 = 22 × 3 × 53. It is the hypotenuse of three different Pythagorean triangles.
1501 = 19 × 79. It is a centered pentagonal number.
1503 = 32 × 167. Completing 12 revolutions of the Spiral of Theodorus requires 1503 triangles.
1510 = 2 × 5 × 151. 1510 is an untouchable number.
1511 is a Sophie Germain prime and a balanced prime.
1513 = 17 × 89. It is a centered square number.
1520 = 24 × 5 × 19. It is a pentagonal number. It forms a Ruth–Aaron pair with 1521 under the second definition.
1521 = 32 × 132 = 392. It is a centered octagonal number. It forms a Ruth–Aaron pair with 1520 under the second definition.
1523 is a super-prime, a safe prime, and a member of the Mian–Chowla sequence.
1525 = 52 × 61. It is a heptagonal number.
1526 = 2 × 7 × 109. There are 1526 conjugacy classes in the alternating group A27.
1529 = 11 × 139. It is a composite de Polignac number.
1530 = 2 × 32 × 5 × 17. It is a vampire number.
1531 is a prime number and a centered decagonal number.
1532 = 22 × 383. There are 1532 series-parallel networks with 9 unlabeled edges,
1600 to 1699
1601 is a Sophie Germain prime and a Proth prime.
1607, 1609, and 1613 form a prime triple.
1617 = 3 × 72 × 11. It is a pentagonal number.
1618 = 2 × 809. It is a centered heptagonal number.
1619 is a safe prime.
1621 is a super-prime.
1624 = 23 × 7 × 29. There are 1624 squares in the Aztec diamond of order 28.
1625 = 53 × 13. It is a centered square number.
1626 = 2 × 3 × 271. It is a centered pentagonal number.
1633 = 23 × 71. It is a star number.
1634 = 2 × 19 × 43. It is the smallest four-digit Narcissistic number in base 10.
1637 is a prime island: it is the smallest prime whose adjacent primes are exactly 30 apart.
1638 = 2 × 32 × 7 × 13. It is a harmonic divisor number.
1639 = 11 × 149. It is a nonagonal number.
1646 = 2 × 823. There are 1646 graphs with 8 nodes and 14 edges.
1649 = 17 × 97. It is a highly cototient number and a Leyland number using 4 and 5: 1649 = 45 + 54.
1651 = 13 × 127. It is a heptagonal number.
1700 to 1799
1705 = 5 × 11 × 13. It is a tribonacci number.
1710 = 2 × 32 × 5 × 19. A maximum of 1710 pieces can be obtained by cutting an annulus 57 times.
1711 = 29 × 59. It is the 58th triangular number and a centered decagonal number.
1717 = 17 × 101. It is a pentagonal number.
1719 = 32 × 131. it is a composite de Polignac number.
1720 = 23 × 5 × 43. It is the sum of the first 31 primes.
1721 is a twin prime with 1723.
1722 = 2 × 3 × 7 × 41. It is a Giuga number and a pronic number.
1723 is a twin prime with 1721. It is also a super-prime.
1733 is a Sophie Germain prime. It is palindromic in bases 3, 18, and 19.
1736 = 23 × 7 × 31. It is the sum of the totient function for the first 75 integers.
1740 = 22 × 3 × 5 × 29. There are 1740 squares in the Aztec diamond of order 29.
1741 is a super-prime and a centered square number.
1747 is a balanced prime.
1750 = 2 × 53 × 7. It is the hypotenuse of three different Pythagorean triangles with integer side lengths.
1753 is a balanced prime.
1800 to 1899
1801 is a cuban prime. It is the sum of five consecutive primes (349 + 353 + 359 + 367 + 373) and nine consecutive primes 179 + 181 + 191 + 193 + 197 + 199 + 211 + 223 + 227).
1806 = 2 × 3 × 301. It is a pronic number, a primary pseudoperfect number, and a Schröder number. It is the only number n such that the denominator of the nth Bernoulli number is n.
1807 = 13 × 139. It is the fifth term of Sylvester's sequence.
1811 is a Sophie Germain prime.
1820 = 22 × 5 × 7 × 13. It is a pentagonal number and a pentatope number.
1821 = 3 × 607. It is a member of the Mian–Chowla sequence.
1823 is a super-prime and a safe prime.
1825 = 52 × 73. It is an octagonal number.
1827 = 32 × 7 × 29. It is a vampire number.
1828 = 22 × 457. It is a meandric number as well as an open meandric number.
1829 = 31 × 59. composite de Polignac number.
1830 = 2 × 3 × 5 × 61. It is the 60th triangular number.
1831 is the smallest prime number with a gap of exactly 16 to the next prime, 1847.
1834 = 2 × 7 × 131. It is an octahedral number.
1837 = 11 × 167. It is a star number.
1841 = 7 × 263. It is the solution to the postage stamp problem with 3 denominations and 29 stamps.
1900 to 1999
1901 is a Sophie Germain prime and a centered decagonal number.
1905 = 3 × 5 × 127. It is a Fermat pseudoprime.
1907 is a safe prime and a balanced prime.
1909 = 23 × 83. It is a hyperperfect number.
1913 is a super-prime.
1918 = 2 × 7 × 137. It is a heptagonal number.
1926 = 2 × 32 × 107. It is a pentagonal number.
1931 is a Sophie Germain prime.
1933 is a prime number and a centered heptagonal number.
1951 is a cuban prime.
1953 = 32 × 7 × 31. It is the 62nd triangular number.
1956 = 22 × 3 × 163. It is a nonagonal number.
1969 = 11 × 179. It is the only number less than four million for which a "mod-ification" of the standard Ackermann Function does not stabilize
1973 is a Sophie Germain prime and a Leonardo prime.
1976 = 23 × 13 × 19. It is an octagonal number.
1980 = 22 × 32 × 5 × 11. It is a pronic number and a highly abundant number, and it also has a greater aliquot sum than any smaller number.
1985 = 5 × 397. It is a centered square number.
Prime numbers
There are 135 prime numbers between 1000 and 2000:
1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987, 1993, 1997, 1999