644672665360 has 80 divisors (see below), whose sum is σ = 1587376008576. Its totient is φ = 242975867904.

The previous prime is 644672665349. The next prime is 644672665363. The reversal of 644672665360 is 63566276446.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (644672665363) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2491389 + ... + 2737948.

Almost surely, 2^644672665360 is an apocalyptic number.

It is an amenable number.

644672665360 is an abundant number, since it is smaller than the sum of its proper divisors (942703343216).

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

644672665360 is a wasteful number, since it uses less digits than its factorization.

644672665360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5229440 (or 5229434 counting only the distinct ones).

The product of its (nonzero) digits is 26127360, while the sum is 55.

The spelling of 644672665360 in words is "six hundred forty-four billion, six hundred seventy-two million, six hundred sixty-five thousand, three hundred sixty".