Adding to 21201100 its reverse (110212), we get a palindrome (21311312).
Almost surely, 221201100 is an apocalyptic number.
21201100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 21201100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23568804).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21201100 is a wasteful number, since it uses less digits than its factorization.
21201100 is an odious number, because the sum of its binary digits is odd.
The square root of 21201100 is about 4604.4652241058. The cubic root of 21201100 is about 276.7702874708.
The spelling of 21201100 in words is "twenty-one million, two hundred one thousand, one hundred".