644377164 has 12 divisors (see below), whose sum is σ = 1503546744. Its totient is φ = 214792384.

The previous prime is 644377159. The next prime is 644377193. The reversal of 644377164 is 461773446.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26849037 + ... + 26849060.

It is an arithmetic number, because the mean of its divisors is an integer number (125295562).

Almost surely, 2^644377164 is an apocalyptic number.

It is an amenable number.

644377164 is an abundant number, since it is smaller than the sum of its proper divisors (859169580).

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

644377164 is a wasteful number, since it uses less digits than its factorization.

644377164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53698104 (or 53698102 counting only the distinct ones).

The product of its digits is 338688, while the sum is 42.

The square root of 644377164 is about 25384.5851650170. The cubic root of 644377164 is about 863.7340627437.

The spelling of 644377164 in words is "six hundred forty-four million, three hundred seventy-seven thousand, one hundred sixty-four".