18978959 has 2 divisors, whose sum is σ = 18978960. Its totient is φ = 18978958.

The previous prime is 18978917. The next prime is 18978989. The reversal of 18978959 is 95987981.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18978959 - 2²⁰ = 17930383 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18978989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9489479 + 9489480.

It is an arithmetic number, because the mean of its divisors is an integer number (9489480).

Almost surely, 2^18978959 is an apocalyptic number.

18978959 is a deficient number, since it is larger than the sum of its proper divisors (1).

18978959 is an equidigital number, since it uses as much as digits as its factorization.

18978959 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1632960, while the sum is 56.

The square root of 18978959 is about 4356.4847067332. The cubic root of 18978959 is about 266.7416270169.

The spelling of 18978959 in words is "eighteen million, nine hundred seventy-eight thousand, nine hundred fifty-nine".