640208704 has 28 divisors (see below), whose sum is σ = 1288316448. Its totient is φ = 315593600.

The previous prime is 640208687. The next prime is 640208707. The reversal of 640208704 is 407802046.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640208707) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65902 + ... + 74989.

Almost surely, 2^640208704 is an apocalyptic number.

640208704 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

640208704 is an abundant number, since it is smaller than the sum of its proper divisors (648107744).

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

640208704 is a wasteful number, since it uses less digits than its factorization.

640208704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140974 (or 140964 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 640208704 is about 25302.3458201013. The cubic root of 640208704 is about 861.8675406525.

The spelling of 640208704 in words is "six hundred forty million, two hundred eight thousand, seven hundred four".