165120216111721 has 8 divisors (see below), whose sum is σ = 179654985334664. Its totient is φ = 150847334622720.

The previous prime is 165120216111659. The next prime is 165120216111751. The reversal of 165120216111721 is 127111612021561.

165120216111721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 42079677003225 + 123040539108496 = 6486885^2 + 11092364^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 165120216111721 - 2⁹ = 165120216111209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165120216111751) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65471932170 + ... + 65471934691.

It is an arithmetic number, because the mean of its divisors is an integer number (22456873166833).

Almost surely, 2^{165120216111721} is an apocalyptic number.

It is an amenable number.

165120216111721 is a deficient number, since it is larger than the sum of its proper divisors (14534769222943).

165120216111721 is a wasteful number, since it uses less digits than its factorization.

165120216111721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130943866971.

The product of its (nonzero) digits is 10080, while the sum is 37.

The spelling of 165120216111721 in words is "one hundred sixty-five trillion, one hundred twenty billion, two hundred sixteen million, one hundred eleven thousand, seven hundred twenty-one".