640684400 has 30 divisors (see below), whose sum is σ = 1539245232. Its totient is φ = 256273600.

The previous prime is 640684399. The next prime is 640684417. The reversal of 640684400 is 4486046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 800456 + ... + 801255.

Almost surely, 2^640684400 is an apocalyptic number.

It is an amenable number.

640684400 is an abundant number, since it is smaller than the sum of its proper divisors (898560832).

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

640684400 is a wasteful number, since it uses less digits than its factorization.

640684400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1601729 (or 1601718 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 32.

The square root of 640684400 is about 25311.7443097073. The cubic root of 640684400 is about 862.0809530581.

The spelling of 640684400 in words is "six hundred forty million, six hundred eighty-four thousand, four hundred".