18978368639 has 2 divisors, whose sum is σ = 18978368640. Its totient is φ = 18978368638.

The previous prime is 18978368623. The next prime is 18978368701. The reversal of 18978368639 is 93686387981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18978368639 - 2⁴ = 18978368623 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18978365639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9489184319 + 9489184320.

It is an arithmetic number, because the mean of its divisors is an integer number (9489184320).

Almost surely, 2^18978368639 is an apocalyptic number.

18978368639 is a deficient number, since it is larger than the sum of its proper divisors (1).

18978368639 is an equidigital number, since it uses as much as digits as its factorization.

18978368639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 94058496, while the sum is 68.

The spelling of 18978368639 in words is "eighteen billion, nine hundred seventy-eight million, three hundred sixty-eight thousand, six hundred thirty-nine".