18644 has 12 divisors (see below), whose sum is σ = 33600. Its totient is φ = 9048.

The previous prime is 18637. The next prime is 18661. The reversal of 18644 is 44681.

It is a happy number.

It is a plaindrome in base 15.

It is a nialpdrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 197 + ... + 275.

It is an arithmetic number, because the mean of its divisors is an integer number (2800).

2¹⁸⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

18644 is a deficient number, since it is larger than the sum of its proper divisors (14956).

18644 is a wasteful number, since it uses less digits than its factorization.

18644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 140 counting only the distinct ones).

The product of its digits is 768, while the sum is 23.

The square root of 18644 is about 136.5430335096. The cubic root of 18644 is about 26.5163065652.

The spelling of 18644 in words is "eighteen thousand, six hundred forty-four".