165221 has 4 divisors (see below), whose sum is σ = 188832. Its totient is φ = 141612.

The previous prime is 165211. The next prime is 165229. The reversal of 165221 is 122561.

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 a de Polignac number, because none of the positive numbers 2^k-165221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 165221.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 165221.

It is not an unprimeable number, because it can be changed into a prime (165229) 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, 11795 + ... + 11808.

It is an arithmetic number, because the mean of its divisors is an integer number (47208).

2¹⁶⁵²²¹ is an apocalyptic number.

It is an amenable number.

165221 is a deficient number, since it is larger than the sum of its proper divisors (23611).

165221 is an equidigital number, since it uses as much as digits as its factorization.

165221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23610.

The product of its digits is 120, while the sum is 17.

The square root of 165221 is about 406.4738613982. The cubic root of 165221 is about 54.8725423217.

Adding to 165221 its reverse (122561), we get a palindrome (287782).

The spelling of 165221 in words is "one hundred sixty-five thousand, two hundred twenty-one".