165905165 has 4 divisors (see below), whose sum is σ = 199086204. Its totient is φ = 132724128.

The previous prime is 165905161. The next prime is 165905183. The reversal of 165905165 is 561509561.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 561509561 = 271 ⋅2071991.

It can be written as a sum of positive squares in 2 ways, for example, as 32410249 + 133494916 = 5693^2 + 11554^2 .

It is a cyclic number.

It is not a de Polignac number, because 165905165 - 2² = 165905161 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165905161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16590512 + ... + 16590521.

It is an arithmetic number, because the mean of its divisors is an integer number (49771551).

Almost surely, 2^165905165 is an apocalyptic number.

It is an amenable number.

165905165 is a deficient number, since it is larger than the sum of its proper divisors (33181039).

165905165 is an equidigital number, since it uses as much as digits as its factorization.

165905165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33181038.

The product of its (nonzero) digits is 40500, while the sum is 38.

The square root of 165905165 is about 12880.4178891836. The cubic root of 165905165 is about 549.4817873730.

The spelling of 165905165 in words is "one hundred sixty-five million, nine hundred five thousand, one hundred sixty-five".