21111220210220 has 144 divisors (see below), whose sum is σ = 53264235467520. Its totient is φ = 7003729547136.

The previous prime is 21111220210217. The next prime is 21111220210229. The reversal of 21111220210220 is 2201202211112.

It is not an unprimeable number, because it can be changed into a prime (21111220210229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2167961 + ... + 6849999.

It is an arithmetic number, because the mean of its divisors is an integer number (369890524080).

Almost surely, 2^{21111220210220} is an apocalyptic number.

21111220210220 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 21111220210220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26632117733760).

21111220210220 is an abundant number, since it is smaller than the sum of its proper divisors (32153015257300).

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

21111220210220 is a wasteful number, since it uses less digits than its factorization.

21111220210220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4682212 (or 4682203 counting only the distinct ones).

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

Adding to 21111220210220 its reverse (2201202211112), we get a palindrome (23312422421332).

The spelling of 21111220210220 in words is "twenty-one trillion, one hundred eleven billion, two hundred twenty million, two hundred ten thousand, two hundred twenty".