640556408 has 32 divisors (see below), whose sum is σ = 1243954800. Its totient is φ = 308861952.

The previous prime is 640556387. The next prime is 640556431. The reversal of 640556408 is 804655046.

640556408 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 376616 + ... + 378312.

Almost surely, 2^640556408 is an apocalyptic number.

It is an amenable number.

640556408 is a deficient number, since it is larger than the sum of its proper divisors (603398392).

640556408 is a wasteful number, since it uses less digits than its factorization.

640556408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3359 (or 3355 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 38.

The square root of 640556408 is about 25309.2158709036. The cubic root of 640556408 is about 862.0235421531.

The spelling of 640556408 in words is "six hundred forty million, five hundred fifty-six thousand, four hundred eight".