640703988 has 36 divisors (see below), whose sum is σ = 1663332580. Its totient is φ = 207795456.

The previous prime is 640703977. The next prime is 640703993. The reversal of 640703988 is 889307046.

It is a happy number.

640703988 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 493372944 + 147331044 = 22212^2 + 12138^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 239173 + ... + 241836.

Almost surely, 2^640703988 is an apocalyptic number.

It is an amenable number.

640703988 is an abundant number, since it is smaller than the sum of its proper divisors (1022628592).

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

640703988 is a wasteful number, since it uses less digits than its factorization.

640703988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481056 (or 481051 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 640703988 is about 25312.1312417584. The cubic root of 640703988 is about 862.0897385952.

The spelling of 640703988 in words is "six hundred forty million, seven hundred three thousand, nine hundred eighty-eight".