638636872831 has 2 divisors, whose sum is σ = 638636872832. Its totient is φ = 638636872830.

The previous prime is 638636872823. The next prime is 638636872847. The reversal of 638636872831 is 138278636836.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638636872831 - 2³ = 638636872823 is a prime.

It is a super-2 number, since 2×638636872831² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 638636872831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638636870831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319318436415 + 319318436416.

It is an arithmetic number, because the mean of its divisors is an integer number (319318436416).

Almost surely, 2^638636872831 is an apocalyptic number.

638636872831 is a deficient number, since it is larger than the sum of its proper divisors (1).

638636872831 is an equidigital number, since it uses as much as digits as its factorization.

638636872831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41803776, while the sum is 61.

The spelling of 638636872831 in words is "six hundred thirty-eight billion, six hundred thirty-six million, eight hundred seventy-two thousand, eight hundred thirty-one".