21221100101220 has 384 divisors, whose sum is σ = 63663806545920. Its totient is φ = 5269954314240.

The previous prime is 21221100101189. The next prime is 21221100101233. The reversal of 21221100101220 is 2210100112212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21221100101220.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 13542500877 + ... + 13542502443.

It is an arithmetic number, because the mean of its divisors is an integer number (165791162880).

Almost surely, 2^{21221100101220} is an apocalyptic number.

21221100101220 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 21221100101220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31831903272960).

21221100101220 is an abundant number, since it is smaller than the sum of its proper divisors (42442706444700).

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

21221100101220 is a wasteful number, since it uses less digits than its factorization.

21221100101220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3315 (or 3313 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21221100101220 its reverse (2210100112212), we get a palindrome (23431200213432).

The spelling of 21221100101220 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred million, one hundred one thousand, two hundred twenty".