285681 has 12 divisors (see below), whose sum is σ = 419216. Its totient is φ = 172920.

The previous prime is 285673. The next prime is 285697. The reversal of 285681 is 186582.

It is not a de Polignac number, because 285681 - 2³ = 285673 is a prime.

It is a super-2 number, since 2×285681² = 163227267522, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 285681.

It is not an unprimeable number, because it can be changed into a prime (285611) 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 11 ways as a sum of consecutive naturals, for example, 31 + ... + 756.

2²⁸⁵⁶⁸¹ is an apocalyptic number.

It is an amenable number.

285681 is a deficient number, since it is larger than the sum of its proper divisors (133535).

285681 is a wasteful number, since it uses less digits than its factorization.

285681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812 (or 801 counting only the distinct ones).

The product of its digits is 3840, while the sum is 30.

The square root of 285681 is about 534.4913469833. The cubic root of 285681 is about 65.8608178071.

Subtracting from 285681 its reverse (186582), we obtain a palindrome (99099).

The spelling of 285681 in words is "two hundred eighty-five thousand, six hundred eighty-one".