165545638129 has 3 divisors (see below), whose sum is σ = 165546045003. Its totient is φ = 165545231256.

The previous prime is 165545638117. The next prime is 165545638151. The reversal of 165545638129 is 921836545561.

The square root of 165545638129 is 406873.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 102620919025 + 62924719104 = 320345^2 + 250848^2 .

It is not a de Polignac number, because 165545638129 - 2²⁵ = 165512083697 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 165545638129.

It is not an unprimeable number, because it can be changed into a prime (165545638109) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 203437 + ... + 610309.

It is an arithmetic number, because the mean of its divisors is an integer number (55182015001).

Almost surely, 2^165545638129 is an apocalyptic number.

165545638129 is the 406873-rd square number.

165545638129 is the 203437-th centered octagonal number.

It is an amenable number.

165545638129 is a deficient number, since it is larger than the sum of its proper divisors (406874).

165545638129 is an frugal number, since it uses more digits than its factorization.

165545638129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 813746 (or 406873 counting only the distinct ones).

The product of its digits is 7776000, while the sum is 55.

The spelling of 165545638129 in words is "one hundred sixty-five billion, five hundred forty-five million, six hundred thirty-eight thousand, one hundred twenty-nine".