521221 has 4 divisors (see below), whose sum is σ = 523692. Its totient is φ = 518752.

The previous prime is 521201. The next prime is 521231. The reversal of 521221 is 122125.

521221 = 510² + 511².

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 260100 + 261121 = 510^2 + 511^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521201) 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, 886 + ... + 1351.

It is an arithmetic number, because the mean of its divisors is an integer number (130923).

2⁵²¹²²¹ is an apocalyptic number.

521221 is the 511-st centered square number.

It is an amenable number.

521221 is a deficient number, since it is larger than the sum of its proper divisors (2471).

521221 is a wasteful number, since it uses less digits than its factorization.

521221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2470.

The product of its digits is 40, while the sum is 13.

The square root of 521221 is about 721.9563698729. The cubic root of 521221 is about 80.4774057959.

Adding to 521221 its reverse (122125), we get a palindrome (643346).

The spelling of 521221 in words is "five hundred twenty-one thousand, two hundred twenty-one".