81166 has 4 divisors (see below), whose sum is σ = 121752. Its totient is φ = 40582.

The previous prime is 81163. The next prime is 81173. The reversal of 81166 is 66118.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (22) 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 (81163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20290 + ... + 20293.

It is an arithmetic number, because the mean of its divisors is an integer number (30438).

2⁸¹¹⁶⁶ is an apocalyptic number.

81166 is a deficient number, since it is larger than the sum of its proper divisors (40586).

81166 is a wasteful number, since it uses less digits than its factorization.

81166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40585.

The product of its digits is 288, while the sum is 22.

The square root of 81166 is about 284.8964724246. The cubic root of 81166 is about 43.2970241542.

The spelling of 81166 in words is "eighty-one thousand, one hundred sixty-six".