644164870528 has 32 divisors (see below), whose sum is σ = 1293093398520. Its totient is φ = 319623782400.

The previous prime is 644164870511. The next prime is 644164870529. The reversal of 644164870528 is 825078461446.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644164870529) 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, 19191393 + ... + 19224928.

Almost surely, 2^644164870528 is an apocalyptic number.

It is an amenable number.

644164870528 is an abundant number, since it is smaller than the sum of its proper divisors (648928527992).

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

644164870528 is a wasteful number, since it uses less digits than its factorization.

644164870528 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38416466 (or 38416454 counting only the distinct ones).

The product of its (nonzero) digits is 10321920, while the sum is 55.

The spelling of 644164870528 in words is "six hundred forty-four billion, one hundred sixty-four million, eight hundred seventy thousand, five hundred twenty-eight".