206666 has 4 divisors (see below), whose sum is σ = 310002. Its totient is φ = 103332.

The previous prime is 206651. The next prime is 206699. The reversal of 206666 is 666602.

206666 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 only one way, i.e., 133225 + 73441 = 365^2 + 271^2 .

206666 is a modest number, since divided by 666 gives 206 as remainder.

It is an unprimeable number.

206666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51665 + ... + 51668.

2²⁰⁶⁶⁶⁶ is an apocalyptic number.

206666 is a deficient number, since it is larger than the sum of its proper divisors (103336).

206666 is a wasteful number, since it uses less digits than its factorization.

206666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103335.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 206666 is about 454.6053233300. The cubic root of 206666 is about 59.1229839134.

The spelling of 206666 in words is "two hundred six thousand, six hundred sixty-six".