816855931 has 2 divisors, whose sum is σ = 816855932. Its totient is φ = 816855930.

The previous prime is 816855929. The next prime is 816855937. The reversal of 816855931 is 139558618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 816855931 - 2¹ = 816855929 is a prime.

It is a super-2 number, since 2×816855931² = 1334507224019753522, which contains 22 as substring.

Together with 816855929, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (816855937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408427965 + 408427966.

It is an arithmetic number, because the mean of its divisors is an integer number (408427966).

Almost surely, 2^816855931 is an apocalyptic number.

816855931 is a deficient number, since it is larger than the sum of its proper divisors (1).

816855931 is an equidigital number, since it uses as much as digits as its factorization.

816855931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 259200, while the sum is 46.

The square root of 816855931 is about 28580.6915766571. The cubic root of 816855931 is about 934.7923627885.

It can be divided in two parts, 81685 and 5931, that added together give a square (87616 = 296²).

The spelling of 816855931 in words is "eight hundred sixteen million, eight hundred fifty-five thousand, nine hundred thirty-one".