18381239 has 2 divisors, whose sum is σ = 18381240. Its totient is φ = 18381238.

The previous prime is 18381229. The next prime is 18381257. The reversal of 18381239 is 93218381.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18381239 - 2²⁰ = 17332663 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 18381199 and 18381208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18381229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9190619 + 9190620.

It is an arithmetic number, because the mean of its divisors is an integer number (9190620).

Almost surely, 2^18381239 is an apocalyptic number.

18381239 is a deficient number, since it is larger than the sum of its proper divisors (1).

18381239 is an equidigital number, since it uses as much as digits as its factorization.

18381239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 35.

The square root of 18381239 is about 4287.3347198464. The cubic root of 18381239 is about 263.9114669082.

The spelling of 18381239 in words is "eighteen million, three hundred eighty-one thousand, two hundred thirty-nine".