281985 has 16 divisors (see below), whose sum is σ = 492480. Its totient is φ = 136640.

The previous prime is 281971. The next prime is 281989. The reversal of 281985 is 589182.

It is a happy number.

It is not a de Polignac number, because 281985 - 2⁶ = 281921 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 281985.

It is not an unprimeable number, because it can be changed into a prime (281989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 690 + ... + 1019.

It is an arithmetic number, because the mean of its divisors is an integer number (30780).

2²⁸¹⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

281985 is a deficient number, since it is larger than the sum of its proper divisors (210495).

281985 is a wasteful number, since it uses less digits than its factorization.

281985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1728.

The product of its digits is 5760, while the sum is 33.

The square root of 281985 is about 531.0225983892. The cubic root of 281985 is about 65.5755591332.

It can be divided in two parts, 28198 and 5, that added together give a triangular number (28203 = T₂₃₇).

The spelling of 281985 in words is "two hundred eighty-one thousand, nine hundred eighty-five".