644379788172 has 24 divisors (see below), whose sum is σ = 1503708934000. Its totient is φ = 214770963456.

The previous prime is 644379788161. The next prime is 644379788197. The reversal of 644379788172 is 271887973446.

It is a super-2 number, since 2×644379788172² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2666797 + ... + 2898372.

Almost surely, 2^644379788172 is an apocalyptic number.

It is an amenable number.

644379788172 is an abundant number, since it is smaller than the sum of its proper divisors (859329145828).

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

644379788172 is a wasteful number, since it uses less digits than its factorization.

644379788172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5574825 (or 5574823 counting only the distinct ones).

The product of its digits is 113799168, while the sum is 66.

The spelling of 644379788172 in words is "six hundred forty-four billion, three hundred seventy-nine million, seven hundred eighty-eight thousand, one hundred seventy-two".