640404664 has 32 divisors (see below), whose sum is σ = 1224253440. Its totient is φ = 313986400.

The previous prime is 640404647. The next prime is 640404689. The reversal of 640404664 is 466404046.

640404664 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, 105537 + ... + 111439.

It is an arithmetic number, because the mean of its divisors is an integer number (38257920).

Almost surely, 2^640404664 is an apocalyptic number.

It is an amenable number.

640404664 is a deficient number, since it is larger than the sum of its proper divisors (583848776).

640404664 is a wasteful number, since it uses less digits than its factorization.

640404664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6171 (or 6167 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 34.

The square root of 640404664 is about 25306.2178920517. The cubic root of 640404664 is about 861.9554673620.

The spelling of 640404664 in words is "six hundred forty million, four hundred four thousand, six hundred sixty-four".