21100120111221 has 16 divisors (see below), whose sum is σ = 28258264609920. Its totient is φ = 14004472285440.

The previous prime is 21100120111171. The next prime is 21100120111223. The reversal of 21100120111221 is 12211102100112.

It is a happy number.

It is not a de Polignac number, because 21100120111221 - 2⁷ = 21100120111093 is a prime.

It is a super-2 number, since 2×21100120111221² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21100120111221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100120111223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13128385 + ... + 14647686.

It is an arithmetic number, because the mean of its divisors is an integer number (1766141538120).

Almost surely, 2^{21100120111221} is an apocalyptic number.

It is an amenable number.

21100120111221 is a deficient number, since it is larger than the sum of its proper divisors (7158144498699).

21100120111221 is a wasteful number, since it uses less digits than its factorization.

21100120111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27777196.

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

Adding to 21100120111221 its reverse (12211102100112), we get a palindrome (33311222211333).

The spelling of 21100120111221 in words is "twenty-one trillion, one hundred billion, one hundred twenty million, one hundred eleven thousand, two hundred twenty-one".