81085 has 4 divisors (see below), whose sum is σ = 97308.
Its totient is φ = 64864.
The previous prime is 81083. The next prime is 81097. The reversal of 81085 is 58018.
81085 = T231 + T232 +
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58018 = 2 ⋅29009.
It can be written as a sum of positive squares in 2 ways, for example, as 47961 + 33124 = 219^2 + 182^2
It is a cyclic number.
It is not a de Polignac number, because 81085 - 21 = 81083 is a prime.
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 Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (81083) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8104 + ... + 8113.
It is an arithmetic number, because the mean of its divisors is an integer number (24327).
281085 is an apocalyptic number.
81085 is the 233-rd centered triangular number.
It is an amenable number.
81085 is a deficient number, since it is larger than the sum of its proper divisors (16223).
81085 is a wasteful number, since it uses less digits than its factorization.
81085 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 16222.
The product of its (nonzero) digits is 320, while the sum is 22.
The square root of 81085 is about 284.7542800381.
The cubic root of 81085 is about 43.2826165360.
The spelling of 81085 in words is "eighty-one thousand, eighty-five".