165272721 has 4 divisors (see below), whose sum is σ = 220363632. Its totient is φ = 110181812.

The previous prime is 165272717. The next prime is 165272741. The reversal of 165272721 is 127272561.

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 165272721 - 2² = 165272717 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not an unprimeable number, because it can be changed into a prime (165272741) 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, 27545451 + ... + 27545456.

It is an arithmetic number, because the mean of its divisors is an integer number (55090908).

Almost surely, 2^165272721 is an apocalyptic number.

It is an amenable number.

165272721 is a deficient number, since it is larger than the sum of its proper divisors (55090911).

165272721 is an equidigital number, since it uses as much as digits as its factorization.

165272721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55090910.

The product of its digits is 11760, while the sum is 33.

The square root of 165272721 is about 12855.8438462825. The cubic root of 165272721 is about 548.7826751540.

The spelling of 165272721 in words is "one hundred sixty-five million, two hundred seventy-two thousand, seven hundred twenty-one".