644974122636 has 48 divisors (see below), whose sum is σ = 1672255943680. Its totient is φ = 214978412880.

The previous prime is 644974122599. The next prime is 644974122649. The reversal of 644974122636 is 636221479446.

644974122636 is a `hidden beast` number, since 6 + 449 + 74 + 122 + 6 + 3 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1711245 + ... + 2053851.

Almost surely, 2^644974122636 is an apocalyptic number.

It is an amenable number.

644974122636 is an abundant number, since it is smaller than the sum of its proper divisors (1027281821044).

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

644974122636 is a wasteful number, since it uses less digits than its factorization.

644974122636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360051 (or 360043 counting only the distinct ones).

The product of its digits is 10450944, while the sum is 54.

The spelling of 644974122636 in words is "six hundred forty-four billion, nine hundred seventy-four million, one hundred twenty-two thousand, six hundred thirty-six".