256904640 has 84 divisors (see below), whose sum is σ = 883654824. Its totient is φ = 68507136.

The previous prime is 256904633. The next prime is 256904651. The reversal of 256904640 is 46409652.

256904640 is a `hidden beast` number, since 2 + 5 + 6 + 9 + 0 + 4 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 256904595 and 256904604.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41722 + ... + 47481.

Almost surely, 2^256904640 is an apocalyptic number.

256904640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256904640 is an abundant number, since it is smaller than the sum of its proper divisors (626750184).

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

256904640 is a wasteful number, since it uses less digits than its factorization.

256904640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89226 (or 89213 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 256904640 is about 16028.2450692520. The cubic root of 256904640 is about 635.7074719754.

The spelling of 256904640 in words is "two hundred fifty-six million, nine hundred four thousand, six hundred forty".