18818 has 6 divisors (see below), whose sum is σ = 28521. Its totient is φ = 9312.

The previous prime is 18803. The next prime is 18839. The reversal of 18818 is 81881.

It can be written as a sum of positive squares in 2 ways, for example, as 18769 + 49 = 137^2 + 7^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=97.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is an unprimeable number.

18818 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 146 + ... + 242.

2¹⁸⁸¹⁸ is an apocalyptic number.

18818 is a deficient number, since it is larger than the sum of its proper divisors (9703).

18818 is an frugal number, since it uses more digits than its factorization.

18818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 99 counting only the distinct ones).

The product of its digits is 512, while the sum is 26.

The square root of 18818 is about 137.1787155502. The cubic root of 18818 is about 26.5985413865.

Multiplying 18818 by its product of digits (512), we get a square (9634816 = 3104²).

The spelling of 18818 in words is "eighteen thousand, eight hundred eighteen".