21211121221212 has 192 divisors, whose sum is σ = 54585100168704. Its totient is φ = 6371196272640.

The previous prime is 21211121221201. The next prime is 21211121221229. The reversal of 21211121221212 is 21212212111212.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 805054623 + ... + 805080969.

It is an arithmetic number, because the mean of its divisors is an integer number (284297396712).

Almost surely, 2^{21211121221212} 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 21211121221212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27292550084352).

21211121221212 is an abundant number, since it is smaller than the sum of its proper divisors (33373978947492).

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

21211121221212 is a wasteful number, since it uses less digits than its factorization.

21211121221212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27188 (or 27186 counting only the distinct ones).

The product of its digits is 128, while the sum is 21.

Adding to 21211121221212 its reverse (21212212111212), we get a palindrome (42423333332424).

The spelling of 21211121221212 in words is "twenty-one trillion, two hundred eleven billion, one hundred twenty-one million, two hundred twenty-one thousand, two hundred twelve".