18991979072639 has 16 divisors (see below), whose sum is σ = 21017032999200. Its totient is φ = 17080509272064.

The previous prime is 18991979072609. The next prime is 18991979072657. The reversal of 18991979072639 is 93627097919981.

It is a cyclic number.

It is not a de Polignac number, because 18991979072639 - 2²⁸ = 18991710637183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18991979072609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 198525809 + ... + 198621450.

It is an arithmetic number, because the mean of its divisors is an integer number (1313564562450).

Almost surely, 2^{18991979072639} is an apocalyptic number.

18991979072639 is a deficient number, since it is larger than the sum of its proper divisors (2025053926561).

18991979072639 is a wasteful number, since it uses less digits than its factorization.

18991979072639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397147402.

The product of its (nonzero) digits is 833299488, while the sum is 80.

The spelling of 18991979072639 in words is "eighteen trillion, nine hundred ninety-one billion, nine hundred seventy-nine million, seventy-two thousand, six hundred thirty-nine".