644637364 has 12 divisors (see below), whose sum is σ = 1289274784. Its totient is φ = 276273144.

The previous prime is 644637361. The next prime is 644637397. The reversal of 644637364 is 463736446.

644637364 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 644637364.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644637361) 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, 11511354 + ... + 11511409.

Almost surely, 2^644637364 is an apocalyptic number.

It is an amenable number.

644637364 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

644637364 is a wasteful number, since it uses less digits than its factorization.

644637364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23022774 (or 23022772 counting only the distinct ones).

The product of its digits is 870912, while the sum is 43.

The square root of 644637364 is about 25389.7098053522. The cubic root of 644637364 is about 863.8503059275.

The spelling of 644637364 in words is "six hundred forty-four million, six hundred thirty-seven thousand, three hundred sixty-four".