81688 has 8 divisors (see below), whose sum is σ = 153180.
Its totient is φ = 40840.
The previous prime is 81677. The next prime is 81689. The reversal of 81688 is 88618.
It is a tau number, because it is divible by the number of its divisors (8).
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 as a sum of consecutive naturals, namely, 5098 + ... + 5113.
281688 is an apocalyptic number.
It is an amenable number.
81688 is a deficient number, since it is larger than the sum of its proper divisors (71492).
81688 is a wasteful number, since it uses less digits than its factorization.
81688 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 10217 (or 10213 counting only the distinct ones).
The product of its digits is 3072, while the sum is 31.
The square root of 81688 is about 285.8111264454.
The cubic root of 81688 is about 43.3896440849.
The spelling of 81688 in words is "eighty-one thousand, six hundred eighty-eight".