205405 has 4 divisors (see below), whose sum is σ = 246492. Its totient is φ = 164320.

The previous prime is 205399. The next prime is 205417. The reversal of 205405 is 504502.

It is a happy number.

205405 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 80089 + 125316 = 283^2 + 354^2 .

It is not a de Polignac number, because 205405 - 2³ = 205397 is a prime.

It is a Duffinian number.

205405 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20536 + ... + 20545.

It is an arithmetic number, because the mean of its divisors is an integer number (61623).

2²⁰⁵⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

205405 is a deficient number, since it is larger than the sum of its proper divisors (41087).

205405 is an equidigital number, since it uses as much as digits as its factorization.

205405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41086.

The product of its (nonzero) digits is 200, while the sum is 16.

The square root of 205405 is about 453.2162839087. The cubic root of 205405 is about 59.0024896010.

Adding to 205405 its reverse (504502), we get a palindrome (709907).

The spelling of 205405 in words is "two hundred five thousand, four hundred five".