520306821 has 40 divisors (see below), whose sum is σ = 805964544. Its totient is φ = 334160640.

The previous prime is 520306817. The next prime is 520306823. The reversal of 520306821 is 128603025.

It is not a de Polignac number, because 520306821 - 2² = 520306817 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (520306823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 886090 + ... + 886676.

Almost surely, 2^520306821 is an apocalyptic number.

It is an amenable number.

520306821 is a deficient number, since it is larger than the sum of its proper divisors (285657723).

520306821 is a wasteful number, since it uses less digits than its factorization.

520306821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983 (or 974 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 520306821 is about 22810.2350053655. The cubic root of 520306821 is about 804.3032799927.

Adding to 520306821 its reverse (128603025), we get a palindrome (648909846).

The spelling of 520306821 in words is "five hundred twenty million, three hundred six thousand, eight hundred twenty-one".