856964921 has 2 divisors, whose sum is σ = 856964922. Its totient is φ = 856964920.

The previous prime is 856964909. The next prime is 856964939. The reversal of 856964921 is 129469658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 843089296 + 13875625 = 29036^2 + 3725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-856964921 is a 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 856964921.

It is not a weakly prime, because it can be changed into another prime (856964971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428482460 + 428482461.

It is an arithmetic number, because the mean of its divisors is an integer number (428482461).

Almost surely, 2^856964921 is an apocalyptic number.

It is an amenable number.

856964921 is a deficient number, since it is larger than the sum of its proper divisors (1).

856964921 is an equidigital number, since it uses as much as digits as its factorization.

856964921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 933120, while the sum is 50.

The square root of 856964921 is about 29273.9631925710. The cubic root of 856964921 is about 949.8485154581.

The spelling of 856964921 in words is "eight hundred fifty-six million, nine hundred sixty-four thousand, nine hundred twenty-one".