21311111200 has 144 divisors (see below), whose sum is σ = 55016478720. Its totient is φ = 8047872000.

The previous prime is 21311111177. The next prime is 21311111203. The reversal of 21311111200 is 211111312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21311111203) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1006321 + ... + 1027279.

It is an arithmetic number, because the mean of its divisors is an integer number (382058880).

Almost surely, 2^21311111200 is an apocalyptic number.

21311111200 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 21311111200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27508239360).

21311111200 is an abundant number, since it is smaller than the sum of its proper divisors (33705367520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21311111200 is a wasteful number, since it uses less digits than its factorization.

21311111200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21051 (or 21038 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 13.

Adding to 21311111200 its reverse (211111312), we get a palindrome (21522222512).

The spelling of 21311111200 in words is "twenty-one billion, three hundred eleven million, one hundred eleven thousand, two hundred".