221525521 has 16 divisors (see below), whose sum is σ = 273542400. Its totient is φ = 178704960.

The previous prime is 221525509. The next prime is 221525533. The reversal of 221525521 is 125525122.

It is an interprime number because it is at equal distance from previous prime (221525509) and next prime (221525533).

It is not a de Polignac number, because 221525521 - 2⁷ = 221525393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221523521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13165 + ... + 24826.

It is an arithmetic number, because the mean of its divisors is an integer number (17096400).

Almost surely, 2^221525521 is an apocalyptic number.

It is an amenable number.

221525521 is a deficient number, since it is larger than the sum of its proper divisors (52016879).

221525521 is an equidigital number, since it uses as much as digits as its factorization.

221525521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38029 (or 38015 counting only the distinct ones).

The product of its digits is 2000, while the sum is 25.

The square root of 221525521 is about 14883.7334362048. The cubic root of 221525521 is about 605.0732065411.

The spelling of 221525521 in words is "two hundred twenty-one million, five hundred twenty-five thousand, five hundred twenty-one".