256568640 has 56 divisors (see below), whose sum is σ = 814608480. Its totient is φ = 68418048.

The previous prime is 256568621. The next prime is 256568699. The reversal of 256568640 is 46865652.

256568640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 256568592 and 256568601.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 132670 + ... + 134589.

It is an arithmetic number, because the mean of its divisors is an integer number (14546580).

Almost surely, 2^256568640 is an apocalyptic number.

256568640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256568640 is an abundant number, since it is smaller than the sum of its proper divisors (558039840).

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

256568640 is a wasteful number, since it uses less digits than its factorization.

256568640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267279 (or 267269 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 42.

The square root of 256568640 is about 16017.7601430412. The cubic root of 256568640 is about 635.4302083984.

The spelling of 256568640 in words is "two hundred fifty-six million, five hundred sixty-eight thousand, six hundred forty".