18639 has 12 divisors (see below), whose sum is σ = 28600. Its totient is φ = 11664.

The previous prime is 18637. The next prime is 18661. The reversal of 18639 is 93681.

18639 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 18639 - 2¹ = 18637 is a prime.

It is a Duffinian number.

18639 is a lucky number.

It is a plaindrome in base 16.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18637) 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, 117 + ... + 225.

2¹⁸⁶³⁹ is an apocalyptic number.

18639 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

18639 is a deficient number, since it is larger than the sum of its proper divisors (9961).

18639 is a wasteful number, since it uses less digits than its factorization.

18639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134 (or 131 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 18639 is about 136.5247230358. The cubic root of 18639 is about 26.5139359476.

It can be divided in two parts, 186 and 39, that added together give a square (225 = 15²).

The spelling of 18639 in words is "eighteen thousand, six hundred thirty-nine".