6689 has 2 divisors, whose sum is σ = 6690.
Its totient is φ = 6688.
The previous prime is 6679. The next prime is 6691. The reversal of 6689 is 9866.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 6400 + 289 = 80^2 + 17^2
It is a cyclic number.
It is not a de Polignac number, because 6689 - 24 = 6673 is a prime.
Together with 6691, it forms a pair of twin primes.
It is a Chen prime.
It is a plaindrome in base 10.
It is not a weakly prime, because it can be changed into another prime (6619) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a good prime.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3344 + 3345.
It is an arithmetic number, because the mean of its divisors is an integer number (3345).
It is an amenable number.
6689 is a deficient number, since it is larger than the sum of its proper divisors (1).
6689 is an equidigital number, since it uses as much as digits as its factorization.
6689 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 2592, while the sum is 29.
The square root of 6689 is about 81.7863069224.
The cubic root of 6689 is about 18.8417136241.
The spelling of 6689 in words is "six thousand, six hundred eighty-nine".