81856759 has 2 divisors, whose sum is σ = 81856760. Its totient is φ = 81856758.

The previous prime is 81856757. The next prime is 81856811. The reversal of 81856759 is 95765818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81856759 - 2¹ = 81856757 is a prime.

Together with 81856757, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81856757) 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, 40928379 + 40928380.

It is an arithmetic number, because the mean of its divisors is an integer number (40928380).

Almost surely, 2^81856759 is an apocalyptic number.

81856759 is a deficient number, since it is larger than the sum of its proper divisors (1).

81856759 is an equidigital number, since it uses as much as digits as its factorization.

81856759 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 604800, while the sum is 49.

The square root of 81856759 is about 9047.4725199914. The cubic root of 81856759 is about 434.1950304540.

The spelling of 81856759 in words is "eighty-one million, eight hundred fifty-six thousand, seven hundred fifty-nine".