520666813 has 2 divisors, whose sum is σ = 520666814. Its totient is φ = 520666812.

The previous prime is 520666807. The next prime is 520666889. The reversal of 520666813 is 318666025.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 381733444 + 138933369 = 19538^2 + 11787^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-520666813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (520664813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260333406 + 260333407.

It is an arithmetic number, because the mean of its divisors is an integer number (260333407).

Almost surely, 2^520666813 is an apocalyptic number.

It is an amenable number.

520666813 is a deficient number, since it is larger than the sum of its proper divisors (1).

520666813 is an equidigital number, since it uses as much as digits as its factorization.

520666813 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 520666813 is about 22818.1246600153. The cubic root of 520666813 is about 804.4887321040.

The spelling of 520666813 in words is "five hundred twenty million, six hundred sixty-six thousand, eight hundred thirteen".