644472164 has 12 divisors (see below), whose sum is σ = 1288944384. Its totient is φ = 276202344.

The previous prime is 644472161. The next prime is 644472187. The reversal of 644472164 is 461274446.

It is a happy number.

644472164 is an admirable number.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (644472161) 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, 11508404 + ... + 11508459.

It is an arithmetic number, because the mean of its divisors is an integer number (107412032).

Almost surely, 2^644472164 is an apocalyptic number.

It is an amenable number.

644472164 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.

644472164 is a wasteful number, since it uses less digits than its factorization.

644472164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23016874 (or 23016872 counting only the distinct ones).

The product of its digits is 129024, while the sum is 38.

The square root of 644472164 is about 25386.4563104030. The cubic root of 644472164 is about 863.7765071942.

The spelling of 644472164 in words is "six hundred forty-four million, four hundred seventy-two thousand, one hundred sixty-four".