205440 has 64 divisors (see below), whose sum is σ = 660960. Its totient is φ = 54272.

The previous prime is 205433. The next prime is 205441. The reversal of 205440 is 44502.

205440 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (205441) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1867 + ... + 1973.

2²⁰⁵⁴⁴⁰ is an apocalyptic number.

205440 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 205440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (330480).

205440 is an abundant number, since it is smaller than the sum of its proper divisors (455520).

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

205440 is a wasteful number, since it uses less digits than its factorization.

205440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 15.

The square root of 205440 is about 453.2548951749. The cubic root of 205440 is about 59.0058406552.

Adding to 205440 its reverse (44502), we get a palindrome (249942).

It can be divided in two parts, 20 and 5440, that added together give a triangular number (5460 = T₁₀₄).

The spelling of 205440 in words is "two hundred five thousand, four hundred forty".