81331759 has 2 divisors, whose sum is σ = 81331760. Its totient is φ = 81331758.

The previous prime is 81331751. The next prime is 81331763. The reversal of 81331759 is 95713318.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81331759 - 2³ = 81331751 is a prime.

It is a super-2 number, since 2×81331759² = 13229710044068162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81331751) 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, 40665879 + 40665880.

It is an arithmetic number, because the mean of its divisors is an integer number (40665880).

Almost surely, 2^81331759 is an apocalyptic number.

81331759 is a deficient number, since it is larger than the sum of its proper divisors (1).

81331759 is an equidigital number, since it uses as much as digits as its factorization.

81331759 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 37.

The square root of 81331759 is about 9018.4122216718. The cubic root of 81331759 is about 433.2647815951.

The spelling of 81331759 in words is "eighty-one million, three hundred thirty-one thousand, seven hundred fifty-nine".