165865 has 12 divisors (see below), whose sum is σ = 231876. Its totient is φ = 113568.

The previous prime is 165857. The next prime is 165877. The reversal of 165865 is 568561.

It can be written as a sum of positive squares in 2 ways, for example, as 127449 + 38416 = 357^2 + 196^2 .

It is not a de Polignac number, because 165865 - 2³ = 165857 is a prime.

It is a super-2 number, since 2×165865² = 55022396450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 94 + ... + 583.

It is an arithmetic number, because the mean of its divisors is an integer number (19323).

2¹⁶⁵⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

165865 is a deficient number, since it is larger than the sum of its proper divisors (66011).

165865 is an equidigital number, since it uses as much as digits as its factorization.

165865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 696 (or 689 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 165865 is about 407.2652698181. The cubic root of 165865 is about 54.9437441321.

The spelling of 165865 in words is "one hundred sixty-five thousand, eight hundred sixty-five".