644568320 has 72 divisors (see below), whose sum is σ = 1684337760. Its totient is φ = 234383360.

The previous prime is 644568299. The next prime is 644568329. The reversal of 644568320 is 23865446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644568329) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8810 + ... + 36969.

It is an arithmetic number, because the mean of its divisors is an integer number (23393580).

Almost surely, 2^644568320 is an apocalyptic number.

It is an amenable number.

644568320 is an abundant number, since it is smaller than the sum of its proper divisors (1039769440).

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

644568320 is a wasteful number, since it uses less digits than its factorization.

644568320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45811 (or 45797 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 38.

The square root of 644568320 is about 25388.3500842414. The cubic root of 644568320 is about 863.8194638793.

The spelling of 644568320 in words is "six hundred forty-four million, five hundred sixty-eight thousand, three hundred twenty".