81965831 has 2 divisors, whose sum is σ = 81965832. Its totient is φ = 81965830.

The previous prime is 81965777. The next prime is 81965833. The reversal of 81965831 is 13856918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81965831 - 2¹⁰ = 81964807 is a prime.

It is a super-2 number, since 2×81965831² = 13436794903041122, which contains 22 as substring.

Together with 81965833, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81965833) 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, 40982915 + 40982916.

It is an arithmetic number, because the mean of its divisors is an integer number (40982916).

Almost surely, 2^81965831 is an apocalyptic number.

81965831 is a deficient number, since it is larger than the sum of its proper divisors (1).

81965831 is an equidigital number, since it uses as much as digits as its factorization.

81965831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 41.

The square root of 81965831 is about 9053.4982741480. The cubic root of 81965831 is about 434.3877960518.

The spelling of 81965831 in words is "eighty-one million, nine hundred sixty-five thousand, eight hundred thirty-one".