18687891979 has 2 divisors, whose sum is σ = 18687891980. Its totient is φ = 18687891978.

The previous prime is 18687891967. The next prime is 18687891983. The reversal of 18687891979 is 97919878681.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18687891979 - 2⁵ = 18687891947 is a prime.

It is not a weakly prime, because it can be changed into another prime (18687891179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9343945989 + 9343945990.

It is an arithmetic number, because the mean of its divisors is an integer number (9343945990).

Almost surely, 2^18687891979 is an apocalyptic number.

18687891979 is a deficient number, since it is larger than the sum of its proper divisors (1).

18687891979 is an equidigital number, since it uses as much as digits as its factorization.

18687891979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 109734912, while the sum is 73.

The spelling of 18687891979 in words is "eighteen billion, six hundred eighty-seven million, eight hundred ninety-one thousand, nine hundred seventy-nine".