Adding to 211111211 its reverse (112111112), we get a palindrome (323222323).
Subtracting from 211111211 its reverse (112111112), we obtain a palindrome (99000099).
211111211 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-211111211 is a prime.
It is a Duffinian number.
Almost surely, 2211111211 is an apocalyptic number.
211111211 is a wasteful number, since it uses less digits than its factorization.
211111211 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1662420.
The square root of 211111211 is about 14529.6665825476. Note that the first 3 decimals coincide. The cubic root of 211111211 is about 595.4387564815.
The spelling of 211111211 in words is "two hundred eleven million, one hundred eleven thousand, two hundred eleven".