18165 has 16 divisors (see below), whose sum is σ = 33408. Its totient is φ = 8256.

The previous prime is 18149. The next prime is 18169. The reversal of 18165 is 56181.

It is not a de Polignac number, because 18165 - 2⁴ = 18149 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an alternating number because its digits alternate between odd and even.

It is a zygodrome in base 6.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18169) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19 + ... + 191.

It is an arithmetic number, because the mean of its divisors is an integer number (2088).

2¹⁸¹⁶⁵ is an apocalyptic number.

18165 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18165 is a deficient number, since it is larger than the sum of its proper divisors (15243).

18165 is a wasteful number, since it uses less digits than its factorization.

18165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188.

The product of its digits is 240, while the sum is 21.

The square root of 18165 is about 134.7775945771. Note that the first 3 decimals coincide. The cubic root of 18165 is about 26.2872487064.

The spelling of 18165 in words is "eighteen thousand, one hundred sixty-five".