81785 has 8 divisors (see below), whose sum is σ = 107136. Its totient is φ = 59440.

The previous prime is 81773. The next prime is 81799. The reversal of 81785 is 58718.

It is a happy number.

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

It is not a de Polignac number, because 81785 - 2⁴ = 81769 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 689 + ... + 798.

It is an arithmetic number, because the mean of its divisors is an integer number (13392).

2⁸¹⁷⁸⁵ is an apocalyptic number.

It is an amenable number.

81785 is a deficient number, since it is larger than the sum of its proper divisors (25351).

81785 is a wasteful number, since it uses less digits than its factorization.

81785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1503.

The product of its digits is 2240, while the sum is 29.

The square root of 81785 is about 285.9807685842. The cubic root of 81785 is about 43.4068115623.

The spelling of 81785 in words is "eighty-one thousand, seven hundred eighty-five".