Adding to 121002121221 its reverse (122121200121), we get a palindrome (243123321342).
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122121200121 = 3 ⋅40707066707.
It is a cyclic number.
It is a self number, because there is not a number n which added to its sum of digits gives 121002121221.
It is a congruent number.
Almost surely, 2121002121221 is an apocalyptic number.
It is an amenable number.
121002121221 is an equidigital number, since it uses as much as digits as its factorization.
121002121221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 40334040410.
The spelling of 121002121221 in words is "one hundred twenty-one billion, two million, one hundred twenty-one thousand, two hundred twenty-one".