165685632025 has 9 divisors (see below), whose sum is σ = 205452707421. Its totient is φ = 132546877440.

The previous prime is 165685631983. The next prime is 165685632043. The reversal of 165685632025 is 520236586561.

The square root of 165685632025 is 407045.

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

It can be written as a sum of positive squares in 4 ways, for example, as 13270348809 + 152415283216 = 115197^2 + 390404^2 .

It is not a de Polignac number, because 165685632025 - 2⁹ = 165685631513 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 165685632025.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1994521 + ... + 2075929.

Almost surely, 2^165685632025 is an apocalyptic number.

165685632025 is the 407045-th square number.

165685632025 is the 203523-rd centered octagonal number.

It is an amenable number.

165685632025 is a deficient number, since it is larger than the sum of its proper divisors (39767075396).

165685632025 is an frugal number, since it uses more digits than its factorization.

165685632025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162828 (or 81414 counting only the distinct ones).

The product of its (nonzero) digits is 2592000, while the sum is 49.

Multiplying 165685632025 by its sum of digits (49), we get a square (8118595969225 = 2849315²).

The spelling of 165685632025 in words is "one hundred sixty-five billion, six hundred eighty-five million, six hundred thirty-two thousand, twenty-five".