18438 has 16 divisors (see below), whose sum is σ = 42240. Its totient is φ = 5256.

The previous prime is 18433. The next prime is 18439. The reversal of 18438 is 83481.

It is a Curzon number.

It is a congruent number.

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

18438 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 178 + ... + 261.

It is an arithmetic number, because the mean of its divisors is an integer number (2640).

2¹⁸⁴³⁸ is an apocalyptic number.

18438 is an abundant number, since it is smaller than the sum of its proper divisors (23802).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21120).

18438 is a wasteful number, since it uses less digits than its factorization.

18438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451.

The product of its digits is 768, while the sum is 24.

The square root of 18438 is about 135.7865972768. The cubic root of 18438 is about 26.4182839365.

It can be divided in two parts, 184 and 38, that added together give a palindrome (222).

The spelling of 18438 in words is "eighteen thousand, four hundred thirty-eight".