85831 has 2 divisors, whose sum is σ = 85832. Its totient is φ = 85830.

The previous prime is 85829. The next prime is 85837. The reversal of 85831 is 13858.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 85831 - 2¹ = 85829 is a prime.

It is a super-2 number, since 2×85831² = 14733921122, which contains 22 as substring.

Together with 85829, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 85796 and 85805.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (85837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42915 + 42916.

It is an arithmetic number, because the mean of its divisors is an integer number (42916).

2⁸⁵⁸³¹ is an apocalyptic number.

85831 is a deficient number, since it is larger than the sum of its proper divisors (1).

85831 is an equidigital number, since it uses as much as digits as its factorization.

85831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 25.

The square root of 85831 is about 292.9692816662. The cubic root of 85831 is about 44.1111172209. Note that the first 5 decimals are identical.

The spelling of 85831 in words is "eighty-five thousand, eight hundred thirty-one".