640646404 has 24 divisors (see below), whose sum is σ = 1153414080. Its totient is φ = 311217504.

The previous prime is 640646399. The next prime is 640646407. The reversal of 640646404 is 404646046.

640646404 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 640646404.

It is not an unprimeable number, because it can be changed into a prime (640646407) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7167 + ... + 36505.

It is an arithmetic number, because the mean of its divisors is an integer number (48058920).

Almost surely, 2^640646404 is an apocalyptic number.

It is an amenable number.

640646404 is a deficient number, since it is larger than the sum of its proper divisors (512767676).

640646404 is a wasteful number, since it uses less digits than its factorization.

640646404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29499 (or 29497 counting only the distinct ones).

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

The square root of 640646404 is about 25310.9937378997. The cubic root of 640646404 is about 862.0639107227.

The spelling of 640646404 in words is "six hundred forty million, six hundred forty-six thousand, four hundred four".