521531221 has 4 divisors (see below), whose sum is σ = 523713600. Its totient is φ = 519348844.

The previous prime is 521531207. The next prime is 521531237. The reversal of 521531221 is 122135125.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 521531221 - 2⁷ = 521531093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 521531192 and 521531201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521531251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1090831 + ... + 1091308.

It is an arithmetic number, because the mean of its divisors is an integer number (130928400).

Almost surely, 2^521531221 is an apocalyptic number.

It is an amenable number.

521531221 is a deficient number, since it is larger than the sum of its proper divisors (2182379).

521531221 is a wasteful number, since it uses less digits than its factorization.

521531221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2182378.

The product of its digits is 600, while the sum is 22.

The square root of 521531221 is about 22837.0580635948. The cubic root of 521531221 is about 804.9336884539.

Adding to 521531221 its reverse (122135125), we get a palindrome (643666346).

The spelling of 521531221 in words is "five hundred twenty-one million, five hundred thirty-one thousand, two hundred twenty-one".