168725521 has 4 divisors (see below), whose sum is σ = 168945700. Its totient is φ = 168505344.

The previous prime is 168725503. The next prime is 168725581. The reversal of 168725521 is 125527861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125527861 = 251 ⋅500111.

It can be written as a sum of positive squares in 2 ways, for example, as 90155025 + 78570496 = 9495^2 + 8864^2 .

It is a cyclic number.

It is not a de Polignac number, because 168725521 - 2⁹ = 168725009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (168725581) 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, 108936 + ... + 110473.

It is an arithmetic number, because the mean of its divisors is an integer number (42236425).

Almost surely, 2^168725521 is an apocalyptic number.

It is an amenable number.

168725521 is a deficient number, since it is larger than the sum of its proper divisors (220179).

168725521 is an equidigital number, since it uses as much as digits as its factorization.

168725521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220178.

The product of its digits is 33600, while the sum is 37.

The square root of 168725521 is about 12989.4388254458. The cubic root of 168725521 is about 552.5780030870.

The spelling of 168725521 in words is "one hundred sixty-eight million, seven hundred twenty-five thousand, five hundred twenty-one".