• 1092 = 11881 is the smallest square that contains exactly three digits '1'.
Subtracting from 109 its sum of digits (10), we obtain a palindrome (99).
It is a happy number.
109 is nontrivially palindromic in base 5 and base 9.
109 is an esthetic number in base 11, because in such base its adjacent digits differ by 1.
It is a weak prime.
It is a cyclic number.
It is a Chen prime.
It is an alternating number because its digits alternate between odd and even.
109 is an undulating number in base 5 and base 9.
It is a plaindrome in base 8, base 11, base 14 and base 16.
It is a nialpdrome in base 12, base 13 and base 15.
It is a congruent number.
It is a Pierpont prime, being equal to 22 ⋅ 33 + 1.
109 is the 9-th centered triangular number.
It is an amenable number.
109 is an equidigital number, since it uses as much as digits as its factorization.
109 is an odious number, because the sum of its binary digits is odd.
The square root of 109 is about 10.4403065089. The cubic root of 109 is about 4.7768561810.
The spelling of 109 in words is "one hundred nine", and thus it is an aban number.