18865 has 16 divisors (see below), whose sum is σ = 28800. Its totient is φ = 11760.

The previous prime is 18859. The next prime is 18869. The reversal of 18865 is 56881.

It is a happy number.

It is not a de Polignac number, because 18865 - 2⁹ = 18353 is a prime.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (18869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1710 + ... + 1720.

It is an arithmetic number, because the mean of its divisors is an integer number (1800).

2¹⁸⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

18865 is a deficient number, since it is larger than the sum of its proper divisors (9935).

18865 is an equidigital number, since it uses as much as digits as its factorization.

18865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37 (or 23 counting only the distinct ones).

The product of its digits is 1920, while the sum is 28.

The square root of 18865 is about 137.3499180924. The cubic root of 18865 is about 26.6206672253.

It can be divided in two parts, 1886 and 5, that added together give a triangular number (1891 = T₆₁).

The spelling of 18865 in words is "eighteen thousand, eight hundred sixty-five".