81285 has 8 divisors (see below), whose sum is σ = 130080. Its totient is φ = 43344.

The previous prime is 81283. The next prime is 81293. The reversal of 81285 is 58218.

81285 = 91² + 92² + ... + 99².

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81285 - 2¹ = 81283 is a prime.

It is an Ulam number.

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81281) 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, 2695 + ... + 2724.

It is an arithmetic number, because the mean of its divisors is an integer number (16260).

2⁸¹²⁸⁵ is an apocalyptic number.

It is an amenable number.

81285 is a deficient number, since it is larger than the sum of its proper divisors (48795).

81285 is a wasteful number, since it uses less digits than its factorization.

81285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5427.

The product of its digits is 640, while the sum is 24.

The square root of 81285 is about 285.1052437259. The cubic root of 81285 is about 43.3181735268.

The spelling of 81285 in words is "eighty-one thousand, two hundred eighty-five".