• Deleting all the even digits from 2209 we obtain a prime of 30 digits.
209 is nontrivially palindromic in base 6, base 9 and base 13.
209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
209 is an esthetic number in base 6, base 8 and base 15, because in such bases its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.
It is a cyclic number.
It is a magnanimous number.
It is an Ulam number.
It is a d-powerful number, because it can be written as 27 + 0 + 92 .
It is a Duffinian number.
209 is an undulating number in base 6, base 9 and base 13.
It is the 19-th Perrin number.
It is a Curzon number.
It is a plaindrome in base 12 and base 15.
It is a nialpdrome in base 8 and base 16.
It is a self number, because there is not a number n which added to its sum of digits gives 209.
It is an amenable number.
209 is a wasteful number, since it uses less digits than its factorization.
209 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 30.
The square root of 209 is about 14.4568322948. The cubic root of 209 is about 5.9344721404.
Subtracting from 209 its product of nonzero digits (18), we obtain a palindrome (191).
Adding to 209 its reverse (902), we get a palindrome (1111).
The spelling of 209 in words is "two hundred nine", and thus it is an aban number.