Subtracting 2109 from its reverse (9012), we obtain a triangular number (6903 = T117).
It is a happy number.
2109 is nontrivially palindromic in base 15.
2109 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a sphenic number, since it is the product of 3 distinct primes.
It is an alternating number because its digits alternate between even and odd.
2109 is an undulating number in base 15.
It is a Curzon number.
It is a plaindrome in base 12.
It is a nialpdrome in base 13 and base 14.
It is a congruent number.
It is an amenable number.
2109 is a wasteful number, since it uses less digits than its factorization.
2109 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 59.
The square root of 2109 is about 45.9238500128. The cubic root of 2109 is about 12.8240595657.
The spelling of 2109 in words is "two thousand, one hundred nine".