520711721 has 2 divisors, whose sum is σ = 520711722. Its totient is φ = 520711720.

The previous prime is 520711699. The next prime is 520711729. The reversal of 520711721 is 127117025.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 512388496 + 8323225 = 22636^2 + 2885^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-520711721 is a prime.

It is a super-2 number, since 2×520711721² = 542281392773563682, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (520711729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260355860 + 260355861.

It is an arithmetic number, because the mean of its divisors is an integer number (260355861).

Almost surely, 2^520711721 is an apocalyptic number.

It is an amenable number.

520711721 is a deficient number, since it is larger than the sum of its proper divisors (1).

520711721 is an equidigital number, since it uses as much as digits as its factorization.

520711721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 980, while the sum is 26.

The square root of 520711721 is about 22819.1086811032. The cubic root of 520711721 is about 804.5118607411.

Adding to 520711721 its reverse (127117025), we get a palindrome (647828746).

The spelling of 520711721 in words is "five hundred twenty million, seven hundred eleven thousand, seven hundred twenty-one".