21212220221000 has 128 divisors (see below), whose sum is σ = 50923587686400. Its totient is φ = 8265920140800.

The previous prime is 21212220220973. The next prime is 21212220221053. The reversal of 21212220221000 is 12202221212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21212220221000.

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 31 ways as a sum of consecutive naturals, for example, 15824996 + ... + 17113004.

It is an arithmetic number, because the mean of its divisors is an integer number (397840528800).

Almost surely, 2^{21212220221000} is an apocalyptic number.

21212220221000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212220221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25461793843200).

21212220221000 is an abundant number, since it is smaller than the sum of its proper divisors (29711367465400).

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

21212220221000 is a wasteful number, since it uses less digits than its factorization.

21212220221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288456 (or 1288442 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21212220221000 its reverse (12202221212), we get a palindrome (21224422442212).

The spelling of 21212220221000 in words is "twenty-one trillion, two hundred twelve billion, two hundred twenty million, two hundred twenty-one thousand".