Adding to 121216 its reverse (612121), we get a palindrome (733337).
121216 is nontrivially palindromic in base 13.
121216 is an esthetic number in base 13, because in such base its adjacent digits differ by 1.
It is a tau number, because it is divible by the number of its divisors (16).
It is an alternating number because its digits alternate between odd and even.
It is a congruent number.
It is an unprimeable number.
2121216 is an apocalyptic number.
121216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.
It is an amenable number.
121216 is an frugal number, since it uses more digits than its factorization.
121216 is an odious number, because the sum of its binary digits is odd.
The square root of 121216 is about 348.1608823518. The cubic root of 121216 is about 49.4902882011.
The spelling of 121216 in words is "one hundred twenty-one thousand, two hundred sixteen".