18515 has 12 divisors (see below), whose sum is σ = 26544. Its totient is φ = 12144.

The previous prime is 18503. The next prime is 18517. The reversal of 18515 is 51581.

18515 = T₄₂ + T₄₃ + ... + T₅₆.

It is not a de Polignac number, because 18515 - 2⁶ = 18451 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (18517) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 794 + ... + 816.

It is an arithmetic number, because the mean of its divisors is an integer number (2212).

2¹⁸⁵¹⁵ is an apocalyptic number.

18515 is a deficient number, since it is larger than the sum of its proper divisors (8029).

18515 is an equidigital number, since it uses as much as digits as its factorization.

18515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58 (or 35 counting only the distinct ones).

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

The square root of 18515 is about 136.0698350113. The cubic root of 18515 is about 26.4550085033.

It can be divided in two parts, 185 and 15, that multiplied together give a triangular number (2775 = T₇₄).

The spelling of 18515 in words is "eighteen thousand, five hundred fifteen".