638865503091 has 12 divisors (see below), whose sum is σ = 923020938840. Its totient is φ = 425811006720.

The previous prime is 638865503063. The next prime is 638865503119. The reversal of 638865503091 is 190305568836.

638865503091 is a `hidden beast` number, since 6 + 3 + 8 + 86 + 550 + 3 + 0 + 9 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (638865503063) and next prime (638865503119).

It is not a de Polignac number, because 638865503091 - 2⁷ = 638865502963 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638865503011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8236645 + ... + 8313846.

It is an arithmetic number, because the mean of its divisors is an integer number (76918411570).

Almost surely, 2^638865503091 is an apocalyptic number.

638865503091 is a deficient number, since it is larger than the sum of its proper divisors (284155435749).

638865503091 is a wasteful number, since it uses less digits than its factorization.

638865503091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16554786 (or 16554783 counting only the distinct ones).

The product of its (nonzero) digits is 4665600, while the sum is 54.

The spelling of 638865503091 in words is "six hundred thirty-eight billion, eight hundred sixty-five million, five hundred three thousand, ninety-one".