856831 has 2 divisors, whose sum is σ = 856832. Its totient is φ = 856830.

The previous prime is 856813. The next prime is 856841. The reversal of 856831 is 138658.

Together with previous prime (856813) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 856831 - 2⁵ = 856799 is a prime.

It is a super-2 number, since 2×856831² = 1468318725122, which contains 22 as substring.

It is a Chen prime.

856831 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 856793 and 856802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (856811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428415 + 428416.

It is an arithmetic number, because the mean of its divisors is an integer number (428416).

2⁸⁵⁶⁸³¹ is an apocalyptic number.

856831 is a deficient number, since it is larger than the sum of its proper divisors (1).

856831 is an equidigital number, since it uses as much as digits as its factorization.

856831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 31.

The square root of 856831 is about 925.6516623439. The cubic root of 856831 is about 94.9799034129.

The spelling of 856831 in words is "eight hundred fifty-six thousand, eight hundred thirty-one".