285840 has 60 divisors (see below), whose sum is σ = 962364. Its totient is φ = 76032.

The previous prime is 285839. The next prime is 285841. The reversal of 285840 is 48582.

285840 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (285839) and next prime (285841).

It can be written as a sum of positive squares in 2 ways, for example, as 147456 + 138384 = 384^2 + 372^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is not an unprimeable number, because it can be changed into a prime (285841) 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 11 ways as a sum of consecutive naturals, for example, 522 + ... + 918.

2²⁸⁵⁸⁴⁰ is an apocalyptic number.

285840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 285840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (481182).

285840 is an abundant number, since it is smaller than the sum of its proper divisors (676524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

285840 is a wasteful number, since it uses less digits than its factorization.

285840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416 (or 407 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 27.

The square root of 285840 is about 534.6400658387. The cubic root of 285840 is about 65.8730341461.

The spelling of 285840 in words is "two hundred eighty-five thousand, eight hundred forty".