Numbers 81,000s

A page of the Numeropedia - the Special Encyclopedia of Numbers

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81,084

[Zip]  U.S. Postal Zip Code: Two Buttes, Colorado 81084.

81,222

[Math.]  812222 = 6,597,013,284, a square number using each of 10 digits 0-9 once. (The 61st of 87 such numbers).

81,225

[Math.]  Three square numbers using the same digits: 1352 = 18225, 1592 = 25281 and 2852 = 81225.

81,249

[Math.]  Its odd powers end with 81249. Its even powers end with 00001.

81,368

[Math.]  One of four numbers that is 1 more or less than the sum of factorials of their digits: 81,368 = (8!+1!+3!+6!+8!)+1. Others: 1466, 372,970 and 372,973.  (References [1])

81,619

[Math.]  816192 = 6,661,661,161, a rare case of non-trivial square number consisting only 2 different digits.

81,796

[Math.]  Four square numbers using the same digits: 1332 = 17689, 1372 = 18769, 2812 = 78961 and 2862 = 81796.

81,799

[Math.]  The 8000th prime number.

817nn

[Zip]  No such U.S. Postal Zip Codes.

818nn

[Zip]  No such U.S. Postal Zip Codes.

81,945

[Math.]  819452 = 6,714,983,025, a square number using each of 10 digits 0-9 once. (The 62nd of 87 such numbers). The 26th and 73rd such number are 54918 and 89145.

819nn

[Zip]  No such U.S. Postal Zip Codes.

81nnn

[Zip]  U.S. Postal Zip Code of Colorado: 80nnn-81nnn.