856593821 has 2 divisors, whose sum is σ = 856593822. Its totient is φ = 856593820.

The previous prime is 856593817. The next prime is 856593839. The reversal of 856593821 is 128395658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 582691321 + 273902500 = 24139^2 + 16550^2 .

It is a cyclic number.

It is not a de Polignac number, because 856593821 - 2² = 856593817 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (856593811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428296910 + 428296911.

It is an arithmetic number, because the mean of its divisors is an integer number (428296911).

Almost surely, 2^856593821 is an apocalyptic number.

It is an amenable number.

856593821 is a deficient number, since it is larger than the sum of its proper divisors (1).

856593821 is an equidigital number, since it uses as much as digits as its factorization.

856593821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518400, while the sum is 47.

The square root of 856593821 is about 29267.6241092440. The cubic root of 856593821 is about 949.7113882284.

The spelling of 856593821 in words is "eight hundred fifty-six million, five hundred ninety-three thousand, eight hundred twenty-one".