18531 has 12 divisors (see below), whose sum is σ = 28080. Its totient is φ = 11760.

The previous prime is 18523. The next prime is 18539. The reversal of 18531 is 13581.

It is a happy number.

18531 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (18523) and next prime (18539).

It is not a de Polignac number, because 18531 - 2³ = 18523 is a prime.

It is a super-2 number, since 2×18531² = 686795922, which contains 22 as substring.

It is a nialpdrome in base 12.

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 18531.

It is not an unprimeable number, because it can be changed into a prime (18539) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 226 + ... + 296.

It is an arithmetic number, because the mean of its divisors is an integer number (2340).

2¹⁸⁵³¹ is an apocalyptic number.

18531 is a deficient number, since it is larger than the sum of its proper divisors (9549).

18531 is a wasteful number, since it uses less digits than its factorization.

18531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106 (or 103 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 18531 is about 136.1286156545. The cubic root of 18531 is about 26.4626267996.

Subtracting from 18531 its reverse (13581), we obtain a triangular number (4950 = T₉₉).

It can be divided in two parts, 185 and 31, that added together give a cube (216 = 6³).

The spelling of 18531 in words is "eighteen thousand, five hundred thirty-one".