Adding to 21100223210221 its reverse (12201232200112), we get a palindrome (33301455410333).
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is a Duffinian number.
It is a congruent number.
Almost surely, 221100223210221 is an apocalyptic number.
It is an amenable number.
21100223210221 is a wasteful number, since it uses less digits than its factorization.
21100223210221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 116575819022.
The spelling of 21100223210221 in words is "twenty-one trillion, one hundred billion, two hundred twenty-three million, two hundred ten thousand, two hundred twenty-one".