165535873321 has 81 divisors (see below), whose sum is σ = 222346476261. Its totient is φ = 122800414464.

The previous prime is 165535873313. The next prime is 165535873331. The reversal of 165535873321 is 123378535561.

The square root of 165535873321 is 406861.

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

165535873321 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 1494672921 + 164041200400 = 38661^2 + 405020^2 .

It is not a de Polignac number, because 165535873321 - 2³ = 165535873313 is a prime.

It is a super-2 number, since 2×165535873321² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

Its product of digits (2268000) is a multiple of the sum of its prime divisors (300).

It is not an unprimeable number, because it can be changed into a prime (165535873331) 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 80 ways as a sum of consecutive naturals, for example, 629413836 + ... + 629414098.

Almost surely, 2^165535873321 is an apocalyptic number.

165535873321 is the 406861-st square number.

165535873321 is the 203431-st centered octagonal number.

It is an amenable number.

165535873321 is a deficient number, since it is larger than the sum of its proper divisors (56810602940).

165535873321 is an equidigital number, since it uses as much as digits as its factorization.

165535873321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600 (or 300 counting only the distinct ones).

The product of its digits is 2268000, while the sum is 49.

Multiplying 165535873321 by its sum of digits (49), we get a square (8111257792729 = 2848027²).

165535873321 divided by its sum of digits (49) gives a square (3378283129 = 58123²).

The spelling of 165535873321 in words is "one hundred sixty-five billion, five hundred thirty-five million, eight hundred seventy-three thousand, three hundred twenty-one".