81985 has 8 divisors (see below), whose sum is σ = 103680. Its totient is φ = 62064.

The previous prime is 81973. The next prime is 82003. The reversal of 81985 is 58918.

81985 = 86² + 87² + ... + 95².

81985 is nontrivially palindromic in base 16.

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

It is a cyclic number.

It is not a de Polignac number, because 81985 - 2⁵ = 81953 is a prime.

81985 is a lucky number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 337 + ... + 526.

It is an arithmetic number, because the mean of its divisors is an integer number (12960).

2⁸¹⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

81985 is a deficient number, since it is larger than the sum of its proper divisors (21695).

81985 is a wasteful number, since it uses less digits than its factorization.

81985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 887.

The product of its digits is 2880, while the sum is 31.

The square root of 81985 is about 286.3302289316. The cubic root of 81985 is about 43.4421656221.

The spelling of 81985 in words is "eighty-one thousand, nine hundred eighty-five".