81686 has 16 divisors (see below), whose sum is σ = 138240. Its totient is φ = 35880.

The previous prime is 81677. The next prime is 81689. The reversal of 81686 is 68618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689) 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, 995 + ... + 1073.

It is an arithmetic number, because the mean of its divisors is an integer number (8640).

2⁸¹⁶⁸⁶ is an apocalyptic number.

81686 is a deficient number, since it is larger than the sum of its proper divisors (56554).

81686 is a wasteful number, since it uses less digits than its factorization.

81686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139.

The product of its digits is 2304, while the sum is 29.

The square root of 81686 is about 285.8076276099. The cubic root of 81686 is about 43.3892899734.

It can be divided in two parts, 81 and 686, that added together give a palindrome (767).

The spelling of 81686 in words is "eighty-one thousand, six hundred eighty-six".