205406905 has 32 divisors (see below), whose sum is σ = 284663808. Its totient is φ = 140817600.

The previous prime is 205406881. The next prime is 205406911. The reversal of 205406905 is 509604502.

205406905 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 205406905 - 2²⁷ = 71189177 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 88672 + ... + 90958.

It is an arithmetic number, because the mean of its divisors is an integer number (8895744).

Almost surely, 2^205406905 is an apocalyptic number.

It is an amenable number.

205406905 is a deficient number, since it is larger than the sum of its proper divisors (79256903).

205406905 is a wasteful number, since it uses less digits than its factorization.

205406905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2397.

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 205406905 is about 14332.0237580043. The cubic root of 205406905 is about 590.0267200386.

The spelling of 205406905 in words is "two hundred five million, four hundred six thousand, nine hundred five".