It is a happy number.
2121212 is nontrivially palindromic in base 10.
2121212 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
It is a nude number because it is divisible by every one of its digits.
It is an alternating number because its digits alternate between even and odd.
2121212 is an undulating number in base 10.
It is a congruent number.
It is an unprimeable number.
22121212 is an apocalyptic number.
It is an amenable number.
2121212 is a wasteful number, since it uses less digits than its factorization.
2121212 is an evil number, because the sum of its binary digits is even.
The square root of 2121212 is about 1456.4381208963. The cubic root of 2121212 is about 128.4876418240.
Multiplying 2121212 by its sum of digits (11), we get a palindrome (23333332).
The spelling of 2121212 in words is "two million, one hundred twenty-one thousand, two hundred twelve".