18321399 has 12 divisors (see below), whose sum is σ = 27027936. Its totient is φ = 11954112.

The previous prime is 18321389. The next prime is 18321419. The reversal of 18321399 is 99312381.

It is not a de Polignac number, because 18321399 - 2⁸ = 18321143 is a prime.

It is a super-2 number, since 2×18321399² = 671347322634402, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18321319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21234 + ... + 22079.

It is an arithmetic number, because the mean of its divisors is an integer number (2252328).

Almost surely, 2^18321399 is an apocalyptic number.

18321399 is a deficient number, since it is larger than the sum of its proper divisors (8706537).

18321399 is a wasteful number, since it uses less digits than its factorization.

18321399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43366 (or 43363 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 18321399 is about 4280.3503361290. The cubic root of 18321399 is about 263.6247682321.

The spelling of 18321399 in words is "eighteen million, three hundred twenty-one thousand, three hundred ninety-nine".