520700021 has 16 divisors (see below), whose sum is σ = 561523248. Its totient is φ = 481075200.

The previous prime is 520700003. The next prime is 520700023. The reversal of 520700021 is 120007025.

It can be written as a sum of positive squares in 8 ways, for example, as 1999396 + 518700625 = 1414^2 + 22775^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-520700021 is a prime.

It is a super-2 number, since 2×520700021² = 542257023738800882, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (520700023) 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 15 ways as a sum of consecutive naturals, for example, 298211 + ... + 299951.

It is an arithmetic number, because the mean of its divisors is an integer number (35095203).

Almost surely, 2^520700021 is an apocalyptic number.

It is an amenable number.

520700021 is a deficient number, since it is larger than the sum of its proper divisors (40823227).

520700021 is a wasteful number, since it uses less digits than its factorization.

520700021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2072.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 520700021 is about 22818.8523155745. The cubic root of 520700021 is about 804.5058351042.

Adding to 520700021 its reverse (120007025), we get a palindrome (640707046).

The spelling of 520700021 in words is "five hundred twenty million, seven hundred thousand, twenty-one".