81759 has 4 divisors (see below), whose sum is σ = 109016. Its totient is φ = 54504.

The previous prime is 81749. The next prime is 81761. The reversal of 81759 is 95718.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 81759 - 2⁵ = 81727 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81749) 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 in 3 ways as a sum of consecutive naturals, for example, 13624 + ... + 13629.

It is an arithmetic number, because the mean of its divisors is an integer number (27254).

2⁸¹⁷⁵⁹ is an apocalyptic number.

81759 is a deficient number, since it is larger than the sum of its proper divisors (27257).

81759 is a wasteful number, since it uses less digits than its factorization.

81759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27256.

The product of its digits is 2520, while the sum is 30.

The square root of 81759 is about 285.9353073686. The cubic root of 81759 is about 43.4022113026.

The spelling of 81759 in words is "eighty-one thousand, seven hundred fifty-nine".