205909409 has 16 divisors (see below), whose sum is σ = 223948800. Its totient is φ = 188752080.

The previous prime is 205909381. The next prime is 205909411. The reversal of 205909409 is 904909502.

205909409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 205909409 - 2⁸ = 205909153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205909439) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 74942 + ... + 77640.

It is an arithmetic number, because the mean of its divisors is an integer number (13996800).

Almost surely, 2^205909409 is an apocalyptic number.

It is an amenable number.

205909409 is a deficient number, since it is larger than the sum of its proper divisors (18039391).

205909409 is a wasteful number, since it uses less digits than its factorization.

205909409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2860.

The product of its (nonzero) digits is 29160, while the sum is 38.

The square root of 205909409 is about 14349.5438603462. The cubic root of 205909409 is about 590.5074720339.

The spelling of 205909409 in words is "two hundred five million, nine hundred nine thousand, four hundred nine".