18720239 has 2 divisors, whose sum is σ = 18720240. Its totient is φ = 18720238.

The previous prime is 18720227. The next prime is 18720257. The reversal of 18720239 is 93202781.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18720239 - 2⁸ = 18719983 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 (18720259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9360119 + 9360120.

It is an arithmetic number, because the mean of its divisors is an integer number (9360120).

Almost surely, 2^18720239 is an apocalyptic number.

18720239 is a deficient number, since it is larger than the sum of its proper divisors (1).

18720239 is an equidigital number, since it uses as much as digits as its factorization.

18720239 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 18720239 is about 4326.6891499159. The cubic root of 18720239 is about 265.5240088327.

The spelling of 18720239 in words is "eighteen million, seven hundred twenty thousand, two hundred thirty-nine".