21012220111220 has 144 divisors (see below), whose sum is σ = 49436588113920. Its totient is φ = 7489627891200.

The previous prime is 21012220111219. The next prime is 21012220111237. The reversal of 21012220111220 is 2211102221012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 802868735 + ... + 802894905.

It is an arithmetic number, because the mean of its divisors is an integer number (343309639680).

Almost surely, 2^{21012220111220} is an apocalyptic number.

21012220111220 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 21012220111220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24718294056960).

21012220111220 is an abundant number, since it is smaller than the sum of its proper divisors (28424368002700).

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

21012220111220 is a wasteful number, since it uses less digits than its factorization.

21012220111220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34426 (or 34411 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21012220111220 its reverse (2211102221012), we get a palindrome (23223322332232).

The spelling of 21012220111220 in words is "twenty-one trillion, twelve billion, two hundred twenty million, one hundred eleven thousand, two hundred twenty".