205666 has 16 divisors (see below), whose sum is σ = 342144. Its totient is φ = 92224.

The previous prime is 205663. The next prime is 205703. The reversal of 205666 is 666502.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 205666.

It is not an unprimeable number, because it can be changed into a prime (205661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 651 + ... + 913.

It is an arithmetic number, because the mean of its divisors is an integer number (21384).

2²⁰⁵⁶⁶⁶ is an apocalyptic number.

205666 is a deficient number, since it is larger than the sum of its proper divisors (136478).

205666 is a wasteful number, since it uses less digits than its factorization.

205666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 205666 is about 453.5041344905. The cubic root of 205666 is about 59.0274697326.

The spelling of 205666 in words is "two hundred five thousand, six hundred sixty-six".