165597721969 has 9 divisors (see below), whose sum is σ = 171124938201. Its totient is φ = 160243651860.

The previous prime is 165597721967. The next prime is 165597722047. The reversal of 165597721969 is 969127795561.

It is a happy number.

The square root of 165597721969 is 406937.

It is a perfect power (a square), and thus also a powerful number.

165597721969 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 165597721969 - 2¹ = 165597721967 is a prime.

It is a super-2 number, since 2×165597721969² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165597721967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 12608484 + ... + 12621610.

Almost surely, 2^165597721969 is an apocalyptic number.

165597721969 is the 406937-th square number.

165597721969 is the 203469-th centered octagonal number.

It is an amenable number.

165597721969 is a deficient number, since it is larger than the sum of its proper divisors (5527216232).

165597721969 is an frugal number, since it uses more digits than its factorization.

165597721969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26316 (or 13158 counting only the distinct ones).

The product of its digits is 64297800, while the sum is 67.

The spelling of 165597721969 in words is "one hundred sixty-five billion, five hundred ninety-seven million, seven hundred twenty-one thousand, nine hundred sixty-nine".