21221220020020 has 96 divisors (see below), whose sum is σ = 44853102798336. Its totient is φ = 8433754982400.

The previous prime is 21221220020009. The next prime is 21221220020173. The reversal of 21221220020020 is 2002002212212.

It is a junction number, because it is equal to n+sod(n) for n = 21221220019976 and 21221220020003.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2635190314 + ... + 2635198366.

It is an arithmetic number, because the mean of its divisors is an integer number (467219820816).

Almost surely, 2^{21221220020020} is an apocalyptic number.

21221220020020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221220020020 is an abundant number, since it is smaller than the sum of its proper divisors (23631882778316).

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

21221220020020 is a wasteful number, since it uses less digits than its factorization.

21221220020020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9721 (or 9719 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21221220020020 its reverse (2002002212212), we get a palindrome (23223222232232).

The spelling of 21221220020020 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty million, twenty thousand, twenty".