256621642525520 has 20 divisors (see below), whose sum is σ = 596645318872020. Its totient is φ = 102648657010176.

The previous prime is 256621642525499. The next prime is 256621642525579. The reversal of 256621642525520 is 25525246126652.

It can be written as a sum of positive squares in 2 ways, for example, as 58821721099024 + 197799921426496 = 7669532^2 + 14064136^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1603885265705 + ... + 1603885265864.

It is an arithmetic number, because the mean of its divisors is an integer number (29832265943601).

Almost surely, 2^{256621642525520} is an apocalyptic number.

256621642525520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256621642525520 is an abundant number, since it is smaller than the sum of its proper divisors (340023676346500).

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

256621642525520 is a wasteful number, since it uses less digits than its factorization.

256621642525520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3207770531582 (or 3207770531576 counting only the distinct ones).

The product of its (nonzero) digits is 17280000, while the sum is 53.

The spelling of 256621642525520 in words is "two hundred fifty-six trillion, six hundred twenty-one billion, six hundred forty-two million, five hundred twenty-five thousand, five hundred twenty".