18155 has 4 divisors (see below), whose sum is σ = 21792. Its totient is φ = 14520.

The previous prime is 18149. The next prime is 18169. The reversal of 18155 is 55181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55181 = 7 ⋅7883.

It is a de Polignac number, because none of the positive numbers 2^k-18155 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

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, 1811 + ... + 1820.

It is an arithmetic number, because the mean of its divisors is an integer number (5448).

2¹⁸¹⁵⁵ is an apocalyptic number.

18155 is a deficient number, since it is larger than the sum of its proper divisors (3637).

18155 is an equidigital number, since it uses as much as digits as its factorization.

18155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3636.

The product of its digits is 200, while the sum is 20.

The square root of 18155 is about 134.7404913157. The cubic root of 18155 is about 26.2824240301.

Subtracting from 18155 its product of digits (200), we obtain a triangular number (17955 = T₁₈₉).

The spelling of 18155 in words is "eighteen thousand, one hundred fifty-five".