21121221120 has 80 divisors (see below), whose sum is σ = 67521928320. Its totient is φ = 5632323584.

The previous prime is 21121221113. The next prime is 21121221137. The reversal of 21121221120 is 2112212112.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×21121221120² (a number of 21 digits) contains 22 as substring.

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 21121221120.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1367400 + ... + 1382759.

It is an arithmetic number, because the mean of its divisors is an integer number (844024104).

Almost surely, 2^21121221120 is an apocalyptic number.

21121221120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121221120 is an abundant number, since it is smaller than the sum of its proper divisors (46400707200).

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

21121221120 is an equidigital number, since it uses as much as digits as its factorization.

21121221120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2750185 (or 2750169 counting only the distinct ones).

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

Adding to 21121221120 its reverse (2112212112), we get a palindrome (23233433232).

The spelling of 21121221120 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty".