256931 has 2 divisors, whose sum is σ = 256932. Its totient is φ = 256930.

The previous prime is 256903. The next prime is 256939. The reversal of 256931 is 139652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256931 - 2¹⁰ = 255907 is a prime.

It is a super-2 number, since 2×256931² = 132027077522, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256931.

It is not a weakly prime, because it can be changed into another prime (256939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128465 + 128466.

It is an arithmetic number, because the mean of its divisors is an integer number (128466).

2²⁵⁶⁹³¹ is an apocalyptic number.

256931 is a deficient number, since it is larger than the sum of its proper divisors (1).

256931 is an equidigital number, since it uses as much as digits as its factorization.

256931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 26.

The square root of 256931 is about 506.8836158331. The cubic root of 256931 is about 63.5729213734.

The spelling of 256931 in words is "two hundred fifty-six thousand, nine hundred thirty-one".