165809565 has 16 divisors (see below), whose sum is σ = 294772800. Its totient is φ = 88431696.

The previous prime is 165809521. The next prime is 165809573. The reversal of 165809565 is 565908561.

It is a happy number.

165809565 is a `hidden beast` number, since 1 + 6 + 5 + 80 + 9 + 565 = 666.

165809565 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 165809565 - 2⁷ = 165809437 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 165809565.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 613975 + ... + 614244.

It is an arithmetic number, because the mean of its divisors is an integer number (18423300).

Almost surely, 2^165809565 is an apocalyptic number.

165809565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

165809565 is a deficient number, since it is larger than the sum of its proper divisors (128963235).

165809565 is a wasteful number, since it uses less digits than its factorization.

165809565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1228233 (or 1228227 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The square root of 165809565 is about 12876.7062947013. The cubic root of 165809565 is about 549.3762239486.

The spelling of 165809565 in words is "one hundred sixty-five million, eight hundred nine thousand, five hundred sixty-five".