18638 has 4 divisors (see below), whose sum is σ = 27960. Its totient is φ = 9318.

The previous prime is 18637. The next prime is 18661. The reversal of 18638 is 83681.

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

It is a Curzon 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 pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4658 + ... + 4661.

It is an arithmetic number, because the mean of its divisors is an integer number (6990).

2¹⁸⁶³⁸ is an apocalyptic number.

18638 is a deficient number, since it is larger than the sum of its proper divisors (9322).

18638 is an equidigital number, since it uses as much as digits as its factorization.

18638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9321.

The product of its digits is 1152, while the sum is 26.

The square root of 18638 is about 136.5210606463. The cubic root of 18638 is about 26.5134617732.

It can be divided in two parts, 18 and 638, that added together give a palindrome (656).

The spelling of 18638 in words is "eighteen thousand, six hundred thirty-eight".