81908759 has 2 divisors, whose sum is σ = 81908760. Its totient is φ = 81908758.

The previous prime is 81908719. The next prime is 81908767. The reversal of 81908759 is 95780918.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81908759 - 2²⁴ = 65131543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81908719) 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, 40954379 + 40954380.

It is an arithmetic number, because the mean of its divisors is an integer number (40954380).

Almost surely, 2^81908759 is an apocalyptic number.

81908759 is a deficient number, since it is larger than the sum of its proper divisors (1).

81908759 is an equidigital number, since it uses as much as digits as its factorization.

81908759 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 47.

The square root of 81908759 is about 9050.3457944987. The cubic root of 81908759 is about 434.2869526629.

The spelling of 81908759 in words is "eighty-one million, nine hundred eight thousand, seven hundred fifty-nine".