640544404 has 12 divisors (see below), whose sum is σ = 1121172724. Its totient is φ = 320209344.

The previous prime is 640544393. The next prime is 640544423. The reversal of 640544404 is 404445046.

It can be written as a sum of positive squares in 2 ways, for example, as 25603600 + 614940804 = 5060^2 + 24798^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13072 + ... + 38104.

Almost surely, 2^640544404 is an apocalyptic number.

It is an amenable number.

640544404 is a deficient number, since it is larger than the sum of its proper divisors (480628320).

640544404 is a wasteful number, since it uses less digits than its factorization.

640544404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31434 (or 31432 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 31.

The square root of 640544404 is about 25308.9787229750. The cubic root of 640544404 is about 862.0181573578.

The spelling of 640544404 in words is "six hundred forty million, five hundred forty-four thousand, four hundred four".