81757 has 8 divisors (see below), whose sum is σ = 92960. Its totient is φ = 71280.

The previous prime is 81749. The next prime is 81761. The reversal of 81757 is 75718.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81757 - 2³ = 81749 is a prime.

It is a Duffinian number.

81757 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82 + ... + 412.

It is an arithmetic number, because the mean of its divisors is an integer number (11620).

2⁸¹⁷⁵⁷ is an apocalyptic number.

It is an amenable number.

81757 is a deficient number, since it is larger than the sum of its proper divisors (11203).

81757 is a wasteful number, since it uses less digits than its factorization.

81757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363.

The product of its digits is 1960, while the sum is 28.

The square root of 81757 is about 285.9318100527. The cubic root of 81757 is about 43.4018573961.

Subtracting from 81757 its product of digits (1960), we obtain a palindrome (79797).

It can be divided in two parts, 81 and 757, that added together give a palindrome (838).

The spelling of 81757 in words is "eighty-one thousand, seven hundred fifty-seven".