1251

1251 = 3² x 139.

1251 is 20001 in base 5.

1251 is a mountain number, where the first and last digits are 1.

1251 is a number n such that 8n - 1 and 8n + 1 are twin primes: 10007 and 10009.

1251 is the sum of three fourth powers: 1251 = 5⁴ + 5⁴ + 1⁴.


The Sharp PC-1251, produced in 1982, was a full-fledged computer in a small, calculator-like package.

Source: Positive Integers