644052164 has 24 divisors (see below), whose sum is σ = 1344110208. Its totient is φ = 264021120.

The previous prime is 644052163. The next prime is 644052193. The reversal of 644052164 is 461250446.

It is a self number, because there is not a number n which added to its sum of digits gives 644052164.

It is not an unprimeable number, because it can be changed into a prime (644052163) 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, 499397 + ... + 500684.

It is an arithmetic number, because the mean of its divisors is an integer number (56004592).

Almost surely, 2^644052164 is an apocalyptic number.

It is an amenable number.

644052164 is an abundant number, since it is smaller than the sum of its proper divisors (700058044).

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

644052164 is a wasteful number, since it uses less digits than its factorization.

644052164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000115 (or 1000113 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 32.

The square root of 644052164 is about 25378.1828348682. The cubic root of 644052164 is about 863.5888264891.

It can be divided in two parts, 6440 and 52164, that multiplied together give a triangular number (335936160 = T₂₅₉₂₀).

The spelling of 644052164 in words is "six hundred forty-four million, fifty-two thousand, one hundred sixty-four".