18815 has 8 divisors (see below), whose sum is σ = 23328. Its totient is φ = 14560.

The previous prime is 18803. The next prime is 18839. The reversal of 18815 is 51881.

18815 = 9² + 10² + ... + 38².

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18815 - 2¹⁰ = 17791 is a prime.

It is a Duffinian number.

It is a plaindrome in base 8 and base 14.

It is a nialpdrome in base 13.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 18815.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 230 + ... + 300.

It is an arithmetic number, because the mean of its divisors is an integer number (2916).

2¹⁸⁸¹⁵ is an apocalyptic number.

18815 is a deficient number, since it is larger than the sum of its proper divisors (4513).

18815 is an equidigital number, since it uses as much as digits as its factorization.

18815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129.

The product of its digits is 320, while the sum is 23.

The square root of 18815 is about 137.1677804734. The cubic root of 18815 is about 26.5971278486.

The spelling of 18815 in words is "eighteen thousand, eight hundred fifteen".