521521221 has 32 divisors (see below), whose sum is σ = 761201280. Its totient is φ = 315684864.

The previous prime is 521521213. The next prime is 521521229. The reversal of 521521221 is 122125125.

It is an interprime number because it is at equal distance from previous prime (521521213) and next prime (521521229).

It is not a de Polignac number, because 521521221 - 2³ = 521521213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521521229) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1204221 + ... + 1204653.

It is an arithmetic number, because the mean of its divisors is an integer number (23787540).

Almost surely, 2^521521221 is an apocalyptic number.

It is an amenable number.

521521221 is a deficient number, since it is larger than the sum of its proper divisors (239680059).

521521221 is a wasteful number, since it uses less digits than its factorization.

521521221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 885.

The product of its digits is 400, while the sum is 21.

The square root of 521521221 is about 22836.8391201585. The cubic root of 521521221 is about 804.9285437390.

Adding to 521521221 its reverse (122125125), we get a palindrome (643646346).

The spelling of 521521221 in words is "five hundred twenty-one million, five hundred twenty-one thousand, two hundred twenty-one".