644752638084 has 24 divisors (see below), whose sum is σ = 1504538039200. Its totient is φ = 214901086464.

The previous prime is 644752638083. The next prime is 644752638227. The reversal of 644752638084 is 480836257446.

It is not an unprimeable number, because it can be changed into a prime (644752638083) 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, 1893709 + ... + 2208084.

Almost surely, 2^644752638084 is an apocalyptic number.

It is an amenable number.

644752638084 is an abundant number, since it is smaller than the sum of its proper divisors (859785401116).

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

644752638084 is a wasteful number, since it uses less digits than its factorization.

644752638084 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4114899 (or 4114897 counting only the distinct ones).

The product of its (nonzero) digits is 30965760, while the sum is 57.

The spelling of 644752638084 in words is "six hundred forty-four billion, seven hundred fifty-two million, six hundred thirty-eight thousand, eighty-four".