21100111201221 has 32 divisors (see below), whose sum is σ = 30332803872000. Its totient is φ = 12969603339264.

The previous prime is 21100111201207. The next prime is 21100111201261. The reversal of 21100111201221 is 12210211100112.

It is a happy number.

It is not a de Polignac number, because 21100111201221 - 2⁶ = 21100111201157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21100111201221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100111201261) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 117296655 + ... + 117476403.

It is an arithmetic number, because the mean of its divisors is an integer number (947900121000).

Almost surely, 2^{21100111201221} is an apocalyptic number.

It is an amenable number.

21100111201221 is a deficient number, since it is larger than the sum of its proper divisors (9232692670779).

21100111201221 is a wasteful number, since it uses less digits than its factorization.

21100111201221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183245.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21100111201221 its reverse (12210211100112), we get a palindrome (33310322301333).

The spelling of 21100111201221 in words is "twenty-one trillion, one hundred billion, one hundred eleven million, two hundred one thousand, two hundred twenty-one".