856285921 has 2 divisors, whose sum is σ = 856285922. Its totient is φ = 856285920.

The previous prime is 856285919. The next prime is 856285949. The reversal of 856285921 is 129582658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 828576225 + 27709696 = 28785^2 + 5264^2 .

It is a cyclic number.

It is not a de Polignac number, because 856285921 - 2¹ = 856285919 is a prime.

Together with 856285919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (856285421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428142960 + 428142961.

It is an arithmetic number, because the mean of its divisors is an integer number (428142961).

Almost surely, 2^856285921 is an apocalyptic number.

It is an amenable number.

856285921 is a deficient number, since it is larger than the sum of its proper divisors (1).

856285921 is an equidigital number, since it uses as much as digits as its factorization.

856285921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 46.

The square root of 856285921 is about 29262.3635579903. The cubic root of 856285921 is about 949.5975843179.

The spelling of 856285921 in words is "eight hundred fifty-six million, two hundred eighty-five thousand, nine hundred twenty-one".