256986731 has 2 divisors, whose sum is σ = 256986732. Its totient is φ = 256986730.

The previous prime is 256986703. The next prime is 256986733. The reversal of 256986731 is 137689652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256986731 - 2²² = 252792427 is a prime.

It is a super-2 number, since 2×256986731² = 132084359820132722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 256986733, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (256986733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128493365 + 128493366.

It is an arithmetic number, because the mean of its divisors is an integer number (128493366).

Almost surely, 2^256986731 is an apocalyptic number.

256986731 is a deficient number, since it is larger than the sum of its proper divisors (1).

256986731 is an equidigital number, since it uses as much as digits as its factorization.

256986731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 47.

The square root of 256986731 is about 16030.8056878000. The cubic root of 256986731 is about 635.7751758318.

The spelling of 256986731 in words is "two hundred fifty-six million, nine hundred eighty-six thousand, seven hundred thirty-one".