206691 has 4 divisors (see below), whose sum is σ = 275592. Its totient is φ = 137792.

The previous prime is 206651. The next prime is 206699. The reversal of 206691 is 196602.

206691 is nontrivially palindromic in base 4.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 206691 - 2⁶ = 206627 is a prime.

It is a D-number.

206691 is a lucky number.

It is a plaindrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (206699) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34446 + ... + 34451.

It is an arithmetic number, because the mean of its divisors is an integer number (68898).

2²⁰⁶⁶⁹¹ is an apocalyptic number.

206691 is a deficient number, since it is larger than the sum of its proper divisors (68901).

206691 is an equidigital number, since it uses as much as digits as its factorization.

206691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68900.

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 206691 is about 454.6328188769. The cubic root of 206691 is about 59.1253678162.

The spelling of 206691 in words is "two hundred six thousand, six hundred ninety-one".