644752638228 has 48 divisors (see below), whose sum is σ = 1514661833216. Its totient is φ = 213459287040.

The previous prime is 644752638227. The next prime is 644752638253. The reversal of 644752638228 is 822836257446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644752638227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 880488 + ... + 1436928.

Almost surely, 2^644752638228 is an apocalyptic number.

It is an amenable number.

644752638228 is an abundant number, since it is smaller than the sum of its proper divisors (869909194988).

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

644752638228 is a wasteful number, since it uses less digits than its factorization.

644752638228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557104 (or 557102 counting only the distinct ones).

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

The spelling of 644752638228 in words is "six hundred forty-four billion, seven hundred fifty-two million, six hundred thirty-eight thousand, two hundred twenty-eight".