520821 has 18 divisors (see below), whose sum is σ = 875862. Its totient is φ = 297360.

The previous prime is 520813. The next prime is 520837. The reversal of 520821 is 128025.

It can be written as a sum of positive squares in only one way, i.e., 509796 + 11025 = 714^2 + 105^2 .

It is not a de Polignac number, because 520821 - 2³ = 520813 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 520794 and 520803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (520841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 150 + ... + 1031.

It is an arithmetic number, because the mean of its divisors is an integer number (48659).

2⁵²⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

520821 is a deficient number, since it is larger than the sum of its proper divisors (355041).

520821 is a wasteful number, since it uses less digits than its factorization.

520821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1201 (or 1191 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 520821 is about 721.6792916525. The cubic root of 520821 is about 80.4568136347.

Adding to 520821 its reverse (128025), we get a palindrome (648846).

The spelling of 520821 in words is "five hundred twenty thousand, eight hundred twenty-one".