520721 has 2 divisors, whose sum is σ = 520722. Its totient is φ = 520720.

The previous prime is 520717. The next prime is 520747. The reversal of 520721 is 127025.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 330625 + 190096 = 575^2 + 436^2 .

It is a cyclic number.

It is not a de Polignac number, because 520721 - 2² = 520717 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 520721.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 520721.

It is not a weakly prime, because it can be changed into another prime (520021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260360 + 260361.

It is an arithmetic number, because the mean of its divisors is an integer number (260361).

2⁵²⁰⁷²¹ is an apocalyptic number.

It is an amenable number.

520721 is a deficient number, since it is larger than the sum of its proper divisors (1).

520721 is an equidigital number, since it uses as much as digits as its factorization.

520721 is an evil number, because the sum of its binary digits is even.

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

The square root of 520721 is about 721.6100054739. The cubic root of 520721 is about 80.4516639470.

Adding to 520721 its reverse (127025), we get a palindrome (647746).

The spelling of 520721 in words is "five hundred twenty thousand, seven hundred twenty-one".