172523521 has 4 divisors (see below), whose sum is σ = 174302212. Its totient is φ = 170744832.

The previous prime is 172523503. The next prime is 172523537. The reversal of 172523521 is 125325271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125325271 = 137 ⋅914783.

It can be written as a sum of positive squares in 2 ways, for example, as 42107121 + 130416400 = 6489^2 + 11420^2 .

It is not a de Polignac number, because 172523521 - 2¹¹ = 172521473 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 172523521.

It is not an unprimeable number, because it can be changed into a prime (172527521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 889200 + ... + 889393.

It is an arithmetic number, because the mean of its divisors is an integer number (43575553).

It is a Proth number, since it is equal to 5265 ⋅ 2¹⁵ + 1 and 5265 < 2¹⁵.

Almost surely, 2^172523521 is an apocalyptic number.

It is an amenable number.

172523521 is a deficient number, since it is larger than the sum of its proper divisors (1778691).

172523521 is an equidigital number, since it uses as much as digits as its factorization.

172523521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1778690.

The product of its digits is 4200, while the sum is 28.

The square root of 172523521 is about 13134.8209352088. The cubic root of 172523521 is about 556.6934408499.

Adding to 172523521 its reverse (125325271), we get a palindrome (297848792).

The spelling of 172523521 in words is "one hundred seventy-two million, five hundred twenty-three thousand, five hundred twenty-one".