256640904135840 has 1152 divisors, whose sum is σ = 977657895422208. Its totient is φ = 56379359232000.

The previous prime is 256640904135829. The next prime is 256640904135871. The reversal of 256640904135840 is 48531409046652.

It is a happy number.

256640904135840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×256640904135840² (a number of 30 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 30189491590 + ... + 30189500090.

It is an arithmetic number, because the mean of its divisors is an integer number (848661367554).

Almost surely, 2^{256640904135840} is an apocalyptic number.

256640904135840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256640904135840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (488828947711104).

256640904135840 is an abundant number, since it is smaller than the sum of its proper divisors (721016991286368).

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

256640904135840 is a wasteful number, since it uses less digits than its factorization.

256640904135840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8990 (or 8975 counting only the distinct ones).

The product of its (nonzero) digits is 24883200, while the sum is 57.

The spelling of 256640904135840 in words is "two hundred fifty-six trillion, six hundred forty billion, nine hundred four million, one hundred thirty-five thousand, eight hundred forty".