21001212012222 has 288 divisors, whose sum is σ = 51105627597024. Its totient is φ = 6192544296960.

The previous prime is 21001212012199. The next prime is 21001212012229. The reversal of 21001212012222 is 22221021210012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21001212012195 and 21001212012204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001212012229) by changing a digit.

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 143 ways as a sum of consecutive naturals, for example, 11818351398 + ... + 11818353174.

It is an arithmetic number, because the mean of its divisors is an integer number (177450095823).

Almost surely, 2^{21001212012222} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21001212012222, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25552813798512).

21001212012222 is an abundant number, since it is smaller than the sum of its proper divisors (30104415584802).

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

21001212012222 is a wasteful number, since it uses less digits than its factorization.

21001212012222 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2216 (or 2142 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21001212012222 its reverse (22221021210012), we get a palindrome (43222233222234).

The spelling of 21001212012222 in words is "twenty-one trillion, one billion, two hundred twelve million, twelve thousand, two hundred twenty-two".