638944509231 has 32 divisors (see below), whose sum is σ = 1116707942400. Its totient is φ = 353333365920.

The previous prime is 638944509199. The next prime is 638944509233. The reversal of 638944509231 is 132905449836.

638944509231 is a `hidden beast` number, since 6 + 3 + 89 + 445 + 0 + 92 + 31 = 666.

It is not a de Polignac number, because 638944509231 - 2⁵ = 638944509199 is a prime.

It is a super-2 number, since 2×638944509231² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638944509233) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54520896 + ... + 54532613.

It is an arithmetic number, because the mean of its divisors is an integer number (34897123200).

Almost surely, 2^638944509231 is an apocalyptic number.

638944509231 is a deficient number, since it is larger than the sum of its proper divisors (477763433169).

638944509231 is a wasteful number, since it uses less digits than its factorization.

638944509231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109053556 (or 109053550 counting only the distinct ones).

The product of its (nonzero) digits is 5598720, while the sum is 54.

The spelling of 638944509231 in words is "six hundred thirty-eight billion, nine hundred forty-four million, five hundred nine thousand, two hundred thirty-one".