21212021021212 has 96 divisors (see below), whose sum is σ = 44379036979200. Its totient is φ = 8863605797760.

The previous prime is 21212021021201. The next prime is 21212021021237. The reversal of 21212021021212 is 21212012021212.

It is a self number, because there is not a number n which added to its sum of digits gives 21212021021212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16333912 + ... + 17584672.

It is an arithmetic number, because the mean of its divisors is an integer number (462281635200).

Almost surely, 2^{21212021021212} 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 21212021021212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22189518489600).

21212021021212 is an abundant number, since it is smaller than the sum of its proper divisors (23167015957988).

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

21212021021212 is a wasteful number, since it uses less digits than its factorization.

21212021021212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1251096 (or 1251080 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21212021021212 its reverse (21212012021212), we get a palindrome (42424033042424).

Subtracting from 21212021021212 its reverse (21212012021212), we obtain a square (9000000 = 3000²).

The spelling of 21212021021212 in words is "twenty-one trillion, two hundred twelve billion, twenty-one million, twenty-one thousand, two hundred twelve".