644868632 has 16 divisors (see below), whose sum is σ = 1211927640. Its totient is φ = 321687936.

The previous prime is 644868593. The next prime is 644868661. The reversal of 644868632 is 236868446.

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, 89618 + ... + 96545.

Almost surely, 2^644868632 is an apocalyptic number.

It is an amenable number.

644868632 is a deficient number, since it is larger than the sum of its proper divisors (567059008).

644868632 is a wasteful number, since it uses less digits than its factorization.

644868632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186602 (or 186598 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 47.

The square root of 644868632 is about 25394.2637617238. The cubic root of 644868632 is about 863.9535976165.

The spelling of 644868632 in words is "six hundred forty-four million, eight hundred sixty-eight thousand, six hundred thirty-two".