809 is nontrivially palindromic in base 11 and base 12.
809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
809 is an esthetic number in base 11, because in such base its adjacent digits differ by 1.
It is a strong prime.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-809 is a prime.
It is a Sophie Germain prime.
It is a Chen prime.
It is a magnanimous number.
809 is an undulating number in base 11 and base 12.
It is a Curzon number.
It is a plaindrome in base 7 and base 15.
It is a good prime.
It is an amenable number.
809 is an equidigital number, since it uses as much as digits as its factorization.
809 is an odious number, because the sum of its binary digits is odd.
The square root of 809 is about 28.4429253067. The cubic root of 809 is about 9.3178598486.
Subtracting from 809 its product of nonzero digits (72), we obtain a palindrome (737).
Subtracting 809 from its reverse (908), we obtain a palindrome (99).