18816 has 48 divisors (see below), whose sum is σ = 58140. Its totient is φ = 5376.

The previous prime is 18803. The next prime is 18839. The reversal of 18816 is 61881.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

Its product of digits (384) is a multiple of the sum of its prime divisors (12).

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2685 + ... + 2691.

2¹⁸⁸¹⁶ is an apocalyptic number.

18816 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29070).

18816 is an abundant number, since it is smaller than the sum of its proper divisors (39324).

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

18816 is an equidigital number, since it uses as much as digits as its factorization.

18816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31 (or 12 counting only the distinct ones).

The product of its digits is 384, while the sum is 24.

The square root of 18816 is about 137.1714255959. The cubic root of 18816 is about 26.5975990446.

Multiplying 18816 by its sum of digits (24), we get a square (451584 = 672²).

18816 divided by its sum of digits (24) gives a square (784 = 28²).

Multiplying 18816 by its product of digits (384), we get a square (7225344 = 2688²).

18816 divided by its product of digits (384) gives a square (49 = 7²).

The spelling of 18816 in words is "eighteen thousand, eight hundred sixteen".