644644264 has 16 divisors (see below), whose sum is σ = 1318590720. Its totient is φ = 293020080.

The previous prime is 644644213. The next prime is 644644289. The reversal of 644644264 is 462446446.

It is a happy 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, 3662664 + ... + 3662839.

It is an arithmetic number, because the mean of its divisors is an integer number (82411920).

Almost surely, 2^644644264 is an apocalyptic number.

It is an amenable number.

644644264 is an abundant number, since it is smaller than the sum of its proper divisors (673946456).

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

644644264 is a wasteful number, since it uses less digits than its factorization.

644644264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7325520 (or 7325516 counting only the distinct ones).

The product of its digits is 442368, while the sum is 40.

The square root of 644644264 is about 25389.8456868095. The cubic root of 644644264 is about 863.8533880458.

The spelling of 644644264 in words is "six hundred forty-four million, six hundred forty-four thousand, two hundred sixty-four".