856521563 has 2 divisors, whose sum is σ = 856521564. Its totient is φ = 856521562.

The previous prime is 856521521. The next prime is 856521569. The reversal of 856521563 is 365125658.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 856521563 - 2⁸ = 856521307 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 856521563.

It is not a weakly prime, because it can be changed into another prime (856521569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428260781 + 428260782.

It is an arithmetic number, because the mean of its divisors is an integer number (428260782).

Almost surely, 2^856521563 is an apocalyptic number.

856521563 is a deficient number, since it is larger than the sum of its proper divisors (1).

856521563 is an equidigital number, since it uses as much as digits as its factorization.

856521563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216000, while the sum is 41.

The square root of 856521563 is about 29266.3896475120. The cubic root of 856521563 is about 949.6846831656.

The spelling of 856521563 in words is "eight hundred fifty-six million, five hundred twenty-one thousand, five hundred sixty-three".