206661 has 16 divisors (see below), whose sum is σ = 339584. Its totient is φ = 108864.

The previous prime is 206651. The next prime is 206699. The reversal of 206661 is 166602.

206661 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 206661 - 2⁶ = 206597 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206641) 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, 106 + ... + 651.

It is an arithmetic number, because the mean of its divisors is an integer number (21224).

2²⁰⁶⁶⁶¹ is an apocalyptic number.

206661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

206661 is a deficient number, since it is larger than the sum of its proper divisors (132923).

206661 is a wasteful number, since it uses less digits than its factorization.

206661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 206661 is about 454.5998240211. The cubic root of 206661 is about 59.1225071097.

The spelling of 206661 in words is "two hundred six thousand, six hundred sixty-one".