856520813 has 2 divisors, whose sum is σ = 856520814. Its totient is φ = 856520812.

The previous prime is 856520803. The next prime is 856520839. The reversal of 856520813 is 318025658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 651372484 + 205148329 = 25522^2 + 14323^2 .

It is a cyclic number.

It is not a de Polignac number, because 856520813 - 2⁸ = 856520557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (856520803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428260406 + 428260407.

It is an arithmetic number, because the mean of its divisors is an integer number (428260407).

Almost surely, 2^856520813 is an apocalyptic number.

It is an amenable number.

856520813 is a deficient number, since it is larger than the sum of its proper divisors (1).

856520813 is an equidigital number, since it uses as much as digits as its factorization.

856520813 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 57600, while the sum is 38.

The square root of 856520813 is about 29266.3768341761. The cubic root of 856520813 is about 949.6844059733.

The spelling of 856520813 in words is "eight hundred fifty-six million, five hundred twenty thousand, eight hundred thirteen".