18039399 has 32 divisors (see below), whose sum is σ = 28723200. Its totient is φ = 10061856.

The previous prime is 18039389. The next prime is 18039401. The reversal of 18039399 is 99393081.

It is a happy number.

It is not a de Polignac number, because 18039399 - 2⁵ = 18039367 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18039399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18039319) 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 in 31 ways as a sum of consecutive naturals, for example, 48177 + ... + 48549.

It is an arithmetic number, because the mean of its divisors is an integer number (897600).

Almost surely, 2^18039399 is an apocalyptic number.

18039399 is a deficient number, since it is larger than the sum of its proper divisors (10683801).

18039399 is an equidigital number, since it uses as much as digits as its factorization.

18039399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444 (or 430 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 42.

The square root of 18039399 is about 4247.2813657680. The cubic root of 18039399 is about 262.2652122838.

The spelling of 18039399 in words is "eighteen million, thirty-nine thousand, three hundred ninety-nine".