21212211200 has 144 divisors (see below), whose sum is σ = 53592624540. Its totient is φ = 8323727360.

The previous prime is 21212211149. The next prime is 21212211217. The reversal of 21212211200 is 211221212.

It can be written as a sum of positive squares in 6 ways, for example, as 3054109696 + 18158101504 = 55264^2 + 134752^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2709692 + ... + 2717508.

Almost surely, 2^21212211200 is an apocalyptic number.

21212211200 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 21212211200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26796312270).

21212211200 is an abundant number, since it is smaller than the sum of its proper divisors (32380413340).

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

21212211200 is an equidigital number, since it uses as much as digits as its factorization.

21212211200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7902 (or 7877 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21212211200 its reverse (211221212), we get a palindrome (21423432412).

It can be divided in two parts, 212122 and 11200, that added together give a palindrome (223322).

The spelling of 21212211200 in words is "twenty-one billion, two hundred twelve million, two hundred eleven thousand, two hundred".