18399 has 4 divisors (see below), whose sum is σ = 24536. Its totient is φ = 12264.

The previous prime is 18397. The next prime is 18401. The reversal of 18399 is 99381.

It is a happy number.

18399 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (18397) and next prime (18401).

It is not a de Polignac number, because 18399 - 2¹ = 18397 is a prime.

It is a D-number.

It is a Duffinian number.

18399 is a lucky number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18397) 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 3 ways as a sum of consecutive naturals, for example, 3064 + ... + 3069.

It is an arithmetic number, because the mean of its divisors is an integer number (6134).

2¹⁸³⁹⁹ is an apocalyptic number.

18399 is a deficient number, since it is larger than the sum of its proper divisors (6137).

18399 is an equidigital number, since it uses as much as digits as its factorization.

18399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6136.

The product of its digits is 1944, while the sum is 30.

The square root of 18399 is about 135.6429135635. The cubic root of 18399 is about 26.3996441642.

It can be divided in two parts, 183 and 99, that added together give a palindrome (282).

The spelling of 18399 in words is "eighteen thousand, three hundred ninety-nine".