123 is nontrivially palindromic in base 6.
123 is an esthetic number in base 6, base 7 and base 10, because in such bases it adjacent digits differ by 1.
It is a cyclic number.
It is a Lucas number.
It is a D-number.
It is an alternating number because its digits alternate between odd and even.
123 is an undulating number in base 6.
It is a straight-line number, since its digits are in arithmetic progression.
It is a plaindrome in base 7, base 9, base 10, base 14 and base 16.
It is a nialpdrome in base 5, base 12, base 13 and base 15.
123 is an equidigital number, since it uses as much as digits as its factorization.
123 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 44.
The square root of 123 is about 11.0905365064. The cubic root of 123 is about 4.9731898333.