165351221 has 4 divisors (see below), whose sum is σ = 188972832. Its totient is φ = 141729612.

The previous prime is 165351161. The next prime is 165351239. The reversal of 165351221 is 122153561.

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, and also an emirpimes, since its reverse is a distinct semiprime: 122153561 = 1069 ⋅114269.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165351221 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 (165351271) 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, 11810795 + ... + 11810808.

It is an arithmetic number, because the mean of its divisors is an integer number (47243208).

Almost surely, 2^165351221 is an apocalyptic number.

It is an amenable number.

165351221 is a deficient number, since it is larger than the sum of its proper divisors (23621611).

165351221 is an equidigital number, since it uses as much as digits as its factorization.

165351221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23621610.

The product of its digits is 1800, while the sum is 26.

The square root of 165351221 is about 12858.8965700794. The cubic root of 165351221 is about 548.8695469641.

The spelling of 165351221 in words is "one hundred sixty-five million, three hundred fifty-one thousand, two hundred twenty-one".