81885 has 16 divisors (see below), whose sum is σ = 134784. Its totient is φ = 42432.

The previous prime is 81883. The next prime is 81899. The reversal of 81885 is 58818.

It is not a de Polignac number, because 81885 - 2¹ = 81883 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 744 + ... + 846.

It is an arithmetic number, because the mean of its divisors is an integer number (8424).

2⁸¹⁸⁸⁵ is an apocalyptic number.

It is an amenable number.

81885 is a deficient number, since it is larger than the sum of its proper divisors (52899).

81885 is a wasteful number, since it uses less digits than its factorization.

81885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164.

The product of its digits is 2560, while the sum is 30.

The square root of 81885 is about 286.1555521041. The cubic root of 81885 is about 43.4244957881.

It can be divided in two parts, 818 and 85, that added together give a triangular number (903 = T₄₂).

The spelling of 81885 in words is "eighty-one thousand, eight hundred eighty-five".