21212222112 has 96 divisors (see below), whose sum is σ = 62469912960. Its totient is φ = 7002063360.

The previous prime is 21212222093. The next prime is 21212222123. The reversal of 21212222112 is 21122221212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

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

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30189 + ... + 208172.

It is an arithmetic number, because the mean of its divisors is an integer number (650728260).

Almost surely, 2^21212222112 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 21212222112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31234956480).

21212222112 is an abundant number, since it is smaller than the sum of its proper divisors (41257690848).

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

21212222112 is a wasteful number, since it uses less digits than its factorization.

21212222112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238483 (or 238469 counting only the distinct ones).

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

Adding to 21212222112 its reverse (21122221212), we get a palindrome (42334443324).

The spelling of 21212222112 in words is "twenty-one billion, two hundred twelve million, two hundred twenty-two thousand, one hundred twelve".