165836809 has 4 divisors (see below), whose sum is σ = 165862660. Its totient is φ = 165810960.

The previous prime is 165836789. The next prime is 165836813. The reversal of 165836809 is 908638561.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 11580409 + 154256400 = 3403^2 + 12420^2 .

It is a cyclic number.

It is not a de Polignac number, because 165836809 - 2⁵ = 165836777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165836899) 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, 4807 + ... + 18835.

It is an arithmetic number, because the mean of its divisors is an integer number (41465665).

Almost surely, 2^165836809 is an apocalyptic number.

It is an amenable number.

165836809 is a deficient number, since it is larger than the sum of its proper divisors (25851).

165836809 is a wasteful number, since it uses less digits than its factorization.

165836809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25850.

The product of its (nonzero) digits is 311040, while the sum is 46.

The square root of 165836809 is about 12877.7641304692. The cubic root of 165836809 is about 549.4063114493.

The spelling of 165836809 in words is "one hundred sixty-five million, eight hundred thirty-six thousand, eight hundred nine".