204840 has 48 divisors (see below), whose sum is σ = 666900. Its totient is φ = 54528.

The previous prime is 204821. The next prime is 204857. The reversal of 204840 is 48402.

It is a happy number.

204840 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 191844 + 12996 = 438^2 + 114^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

204840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 76 + ... + 644.

2²⁰⁴⁸⁴⁰ is an apocalyptic number.

204840 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 204840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (333450).

204840 is an abundant number, since it is smaller than the sum of its proper divisors (462060).

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

204840 is a wasteful number, since it uses less digits than its factorization.

204840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 586 (or 579 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 204840 is about 452.5925319755. The cubic root of 204840 is about 58.9483412612.

The spelling of 204840 in words is "two hundred four thousand, eight hundred forty".