521521 has 16 divisors (see below), whose sum is σ = 701568. Its totient is φ = 374400.

The previous prime is 521519. The next prime is 521527. The reversal of 521521 is 125125.

521521 = 26² + 27² + ... + 116².

It is not a de Polignac number, because 521521 - 2¹ = 521519 is a prime.

521521 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 521495 and 521504.

It is not an unprimeable number, because it can be changed into a prime (521527) 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, 741 + ... + 1261.

It is an arithmetic number, because the mean of its divisors is an integer number (43848).

2⁵²¹⁵²¹ is an apocalyptic number.

It is an amenable number.

521521 is a deficient number, since it is larger than the sum of its proper divisors (180047).

521521 is a wasteful number, since it uses less digits than its factorization.

521521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 552.

The product of its digits is 100, while the sum is 16.

The square root of 521521 is about 722.1641087731. The cubic root of 521521 is about 80.4928430040.

Adding to 521521 its reverse (125125), we get a palindrome (646646).

The spelling of 521521 in words is "five hundred twenty-one thousand, five hundred twenty-one".