256631138531 has 2 divisors, whose sum is σ = 256631138532. Its totient is φ = 256631138530.

The previous prime is 256631138503. The next prime is 256631138537. The reversal of 256631138531 is 135831136652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256631138531 - 2²² = 256626944227 is a prime.

It is a super-2 number, since 2×256631138531² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (256631138537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128315569265 + 128315569266.

It is an arithmetic number, because the mean of its divisors is an integer number (128315569266).

Almost surely, 2^256631138531 is an apocalyptic number.

256631138531 is a deficient number, since it is larger than the sum of its proper divisors (1).

256631138531 is an equidigital number, since it uses as much as digits as its factorization.

256631138531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 388800, while the sum is 44.

The spelling of 256631138531 in words is "two hundred fifty-six billion, six hundred thirty-one million, one hundred thirty-eight thousand, five hundred thirty-one".