21021221220220 has 72 divisors (see below), whose sum is σ = 49093443753984. Its totient is φ = 7551906455808.

The previous prime is 21021221220119. The next prime is 21021221220283. The reversal of 21021221220220 is 2202212212012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 83919484 + ... + 84169603.

It is an arithmetic number, because the mean of its divisors is an integer number (681853385472).

Almost surely, 2^{21021221220220} is an apocalyptic number.

21021221220220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021221220220 is an abundant number, since it is smaller than the sum of its proper divisors (28072222533764).

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

21021221220220 is a wasteful number, since it uses less digits than its factorization.

21021221220220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168089159 (or 168089144 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21021221220220 its reverse (2202212212012), we get a palindrome (23223433432232).

The spelling of 21021221220220 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-one million, two hundred twenty thousand, two hundred twenty".