256920138 has 48 divisors (see below), whose sum is σ = 564069480. Its totient is φ = 84509568.

The previous prime is 256920137. The next prime is 256920163. The reversal of 256920138 is 831029652.

It can be written as a sum of positive squares in 4 ways, for example, as 251000649 + 5919489 = 15843^2 + 2433^2 .

It is not an unprimeable number, because it can be changed into a prime (256920137) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 646956 + ... + 647352.

Almost surely, 2^256920138 is an apocalyptic number.

256920138 is an abundant number, since it is smaller than the sum of its proper divisors (307149342).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256920138 is a wasteful number, since it uses less digits than its factorization.

256920138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 791 (or 788 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 256920138 is about 16028.7285210025. The cubic root of 256920138 is about 635.7202549238.

The spelling of 256920138 in words is "two hundred fifty-six million, nine hundred twenty thousand, one hundred thirty-eight".