18431 has 4 divisors (see below), whose sum is σ = 21072. Its totient is φ = 15792.

The previous prime is 18427. The next prime is 18433. The reversal of 18431 is 13481.

18431 = 19² + 20² + ... + 39².

It is a happy number.

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

It is not a de Polignac number, because 18431 - 2² = 18427 is a prime.

It is a super-2 number, since 2×18431² = 679403522, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a zygodrome in base 6.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 18431.

It is not an unprimeable number, because it can be changed into a prime (18433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1310 + ... + 1323.

It is an arithmetic number, because the mean of its divisors is an integer number (5268).

2¹⁸⁴³¹ is an apocalyptic number.

18431 is a deficient number, since it is larger than the sum of its proper divisors (2641).

18431 is an equidigital number, since it uses as much as digits as its factorization.

18431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2640.

The product of its digits is 96, while the sum is 17.

The square root of 18431 is about 135.7608190900. The cubic root of 18431 is about 26.4149402731.

Subtracting from 18431 its reverse (13481), we obtain a triangular number (4950 = T₉₉).

The spelling of 18431 in words is "eighteen thousand, four hundred thirty-one".