Adding to 21220101212111 its reverse (11121210102212), we get a palindrome (32341311314323).
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-21220101212111 is a prime.
It is a Duffinian number.
It is a self number, because there is not a number n which added to its sum of digits gives 21220101212111.
It is a congruent number.
Almost surely, 221220101212111 is an apocalyptic number.
21220101212111 is a wasteful number, since it uses less digits than its factorization.
21220101212111 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1374841.
The spelling of 21220101212111 in words is "twenty-one trillion, two hundred twenty billion, one hundred one million, two hundred twelve thousand, one hundred eleven".