165599221 has 4 divisors (see below), whose sum is σ = 165635200. Its totient is φ = 165563244.

The previous prime is 165599209. The next prime is 165599249. The reversal of 165599221 is 122995561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 165599221 - 2¹³ = 165591029 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 (165599281) 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, 9861 + ... + 20698.

It is an arithmetic number, because the mean of its divisors is an integer number (41408800).

Almost surely, 2^165599221 is an apocalyptic number.

It is an amenable number.

165599221 is a deficient number, since it is larger than the sum of its proper divisors (35979).

165599221 is an equidigital number, since it uses as much as digits as its factorization.

165599221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35978.

The product of its digits is 48600, while the sum is 40.

The square root of 165599221 is about 12868.5360861288. The cubic root of 165599221 is about 549.1438149758.

The spelling of 165599221 in words is "one hundred sixty-five million, five hundred ninety-nine thousand, two hundred twenty-one".