165884329521 has 27 divisors (see below), whose sum is σ = 241738387371. Its totient is φ = 109616132304.

The previous prime is 165884329483. The next prime is 165884329543. The reversal of 165884329521 is 125923488561.

The square root of 165884329521 is 407289.

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

165884329521 is a `hidden beast` number, since 1 + 6 + 5 + 8 + 84 + 32 + 9 + 521 = 666.

It can be written as a sum of positive squares in only one way, i.e., 77568377121 + 88315952400 = 278511^2 + 297180^2 .

It is not a de Polignac number, because 165884329521 - 2²⁵ = 165850775089 is a prime.

It is a super-2 number, since 2×165884329521² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (165884329921) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 155176575 + ... + 155177643.

Almost surely, 2^165884329521 is an apocalyptic number.

165884329521 is the 407289-th square number.

165884329521 is the 203645-th centered octagonal number.

It is an amenable number.

165884329521 is a deficient number, since it is larger than the sum of its proper divisors (75854057850).

165884329521 is an frugal number, since it uses more digits than its factorization.

165884329521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2398 (or 1199 counting only the distinct ones).

The product of its digits is 4147200, while the sum is 54.

The spelling of 165884329521 in words is "one hundred sixty-five billion, eight hundred eighty-four million, three hundred twenty-nine thousand, five hundred twenty-one".