644634988 has 6 divisors (see below), whose sum is σ = 1128111236. Its totient is φ = 322317492.

The previous prime is 644634971. The next prime is 644635009. The reversal of 644634988 is 889436446.

It is a happy number.

644634988 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80579370 + ... + 80579377.

Almost surely, 2^644634988 is an apocalyptic number.

It is an amenable number.

644634988 is a deficient number, since it is larger than the sum of its proper divisors (483476248).

644634988 is a wasteful number, since it uses less digits than its factorization.

644634988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161158751 (or 161158749 counting only the distinct ones).

The product of its digits is 3981312, while the sum is 52.

The square root of 644634988 is about 25389.6630146995. The cubic root of 644634988 is about 863.8492446017.

The spelling of 644634988 in words is "six hundred forty-four million, six hundred thirty-four thousand, nine hundred eighty-eight".