165565 has 4 divisors (see below), whose sum is σ = 198684. Its totient is φ = 132448.

The previous prime is 165559. The next prime is 165569. The reversal of 165565 is 565561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 565561 = 79 ⋅7159.

It can be written as a sum of positive squares in 2 ways, for example, as 49284 + 116281 = 222^2 + 341^2 .

It is a cyclic number.

It is not a de Polignac number, because 165565 - 2⁵ = 165533 is a prime.

It is a Duffinian number.

165565 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16552 + ... + 16561.

It is an arithmetic number, because the mean of its divisors is an integer number (49671).

2¹⁶⁵⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

165565 is a deficient number, since it is larger than the sum of its proper divisors (33119).

165565 is an equidigital number, since it uses as much as digits as its factorization.

165565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33118.

The product of its digits is 4500, while the sum is 28.

The square root of 165565 is about 406.8967928112. The cubic root of 165565 is about 54.9105985601.

It can be divided in two parts, 16556 and 5, that added together give a palindrome (16561).

The spelling of 165565 in words is "one hundred sixty-five thousand, five hundred sixty-five".