644360064 has 32 divisors (see below), whose sum is σ = 1711582440. Its totient is φ = 214786560.

The previous prime is 644360051. The next prime is 644360071. The reversal of 644360064 is 460063446.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 838627 + ... + 839394.

Almost surely, 2^644360064 is an apocalyptic number.

644360064 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

644360064 is an abundant number, since it is smaller than the sum of its proper divisors (1067222376).

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

644360064 is a wasteful number, since it uses less digits than its factorization.

644360064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1678038 (or 1678026 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 33.

The square root of 644360064 is about 25384.2483441996. The cubic root of 644360064 is about 863.7264222996.

The spelling of 644360064 in words is "six hundred forty-four million, three hundred sixty thousand, sixty-four".