21120121220 has 192 divisors, whose sum is σ = 51492672000. Its totient is φ = 7201751040.

The previous prime is 21120121199. The next prime is 21120121229. The reversal of 21120121220 is 2212102112.

It is a junction number, because it is equal to n+sod(n) for n = 21120121195 and 21120121204.

It is not an unprimeable number, because it can be changed into a prime (21120121229) 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 63 ways as a sum of consecutive naturals, for example, 82179332 + ... + 82179588.

It is an arithmetic number, because the mean of its divisors is an integer number (268191000).

Almost surely, 2^21120121220 is an apocalyptic number.

21120121220 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 21120121220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25746336000).

21120121220 is an abundant number, since it is smaller than the sum of its proper divisors (30372550780).

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

21120121220 is a wasteful number, since it uses less digits than its factorization.

21120121220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 558 (or 556 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21120121220 its reverse (2212102112), we get a palindrome (23332223332).

The spelling of 21120121220 in words is "twenty-one billion, one hundred twenty million, one hundred twenty-one thousand, two hundred twenty".