18918139 has 2 divisors, whose sum is σ = 18918140. Its totient is φ = 18918138.

The previous prime is 18918101. The next prime is 18918143. The reversal of 18918139 is 93181981.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18918139 - 2²¹ = 16820987 is a prime.

It is not a weakly prime, because it can be changed into another prime (18918199) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459069 + 9459070.

It is an arithmetic number, because the mean of its divisors is an integer number (9459070).

Almost surely, 2^18918139 is an apocalyptic number.

18918139 is a deficient number, since it is larger than the sum of its proper divisors (1).

18918139 is an equidigital number, since it uses as much as digits as its factorization.

18918139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 40.

The square root of 18918139 is about 4349.4987067477. The cubic root of 18918139 is about 266.4563885706.

It can be divided in two parts, 189 and 18139, that multiplied together give a triangular number (3428271 = T₂₆₁₈).

The spelling of 18918139 in words is "eighteen million, nine hundred eighteen thousand, one hundred thirty-nine".