21100111221220 has 24 divisors (see below), whose sum is σ = 44339992011000. Its totient is φ = 8434376212992.

The previous prime is 21100111221181. The next prime is 21100111221227. The reversal of 21100111221220 is 2212211100112.

It can be written as a sum of positive squares in 4 ways, for example, as 5700404552704 + 15399706668516 = 2387552^2 + 3924246^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21100111221194 and 21100111221203.

It is not an unprimeable number, because it can be changed into a prime (21100111221227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 354236695 + ... + 354296254.

It is an arithmetic number, because the mean of its divisors is an integer number (1847499667125).

Almost surely, 2^{21100111221220} is an apocalyptic number.

21100111221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100111221220 is an abundant number, since it is smaller than the sum of its proper divisors (23239880789780).

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

21100111221220 is a wasteful number, since it uses less digits than its factorization.

21100111221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 708534447 (or 708534445 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21100111221220 its reverse (2212211100112), we get a palindrome (23312322321332).

The spelling of 21100111221220 in words is "twenty-one trillion, one hundred billion, one hundred eleven million, two hundred twenty-one thousand, two hundred twenty".