21212122112 has 66 divisors (see below), whose sum is σ = 43466513844. Its totient is φ = 10346536960.

The previous prime is 21212122081. The next prime is 21212122187. The reversal of 21212122112 is 21122121212.

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1715183 + ... + 1727505.

Almost surely, 2^21212122112 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212122112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21733256922).

21212122112 is an abundant number, since it is smaller than the sum of its proper divisors (22254391732).

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

21212122112 is an equidigital number, since it uses as much as digits as its factorization.

21212122112 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12425 (or 12366 counting only the distinct ones).

The product of its digits is 64, while the sum is 17.

Adding to 21212122112 its reverse (21122121212), we get a palindrome (42334243324).

It can be divided in two parts, 2121212 and 2112, that multiplied together give a palindrome (4479999744).

The spelling of 21212122112 in words is "twenty-one billion, two hundred twelve million, one hundred twenty-two thousand, one hundred twelve".