81789 has 8 divisors (see below), whose sum is σ = 110400. Its totient is φ = 53856.

The previous prime is 81773. The next prime is 81799. The reversal of 81789 is 98718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81789 - 2⁴ = 81773 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax 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 7 ways as a sum of consecutive naturals, for example, 312 + ... + 510.

It is an arithmetic number, because the mean of its divisors is an integer number (13800).

2⁸¹⁷⁸⁹ is an apocalyptic number.

It is an amenable number.

81789 is a deficient number, since it is larger than the sum of its proper divisors (28611).

81789 is a wasteful number, since it uses less digits than its factorization.

81789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339.

The product of its digits is 4032, while the sum is 33.

The square root of 81789 is about 285.9877619759. The cubic root of 81789 is about 43.4075192080.

The spelling of 81789 in words is "eighty-one thousand, seven hundred eighty-nine".