21101222101221 has 24 divisors (see below), whose sum is σ = 31304138054904. Its totient is φ = 13686919090560.

The previous prime is 21101222101177. The next prime is 21101222101277. The reversal of 21101222101221 is 12210122210112.

21101222101221 is a `hidden beast` number, since 2 + 110 + 122 + 210 + 1 + 221 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 337980612321 + 20763241488900 = 581361^2 + 4556670^2 .

It is not a de Polignac number, because 21101222101221 - 2⁹ = 21101222100709 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21101222101194 and 21101222101203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101222101121) 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 23 ways as a sum of consecutive naturals, for example, 12145231 + ... + 13773491.

It is an arithmetic number, because the mean of its divisors is an integer number (1304339085621).

Almost surely, 2^{21101222101221} is an apocalyptic number.

It is an amenable number.

21101222101221 is a deficient number, since it is larger than the sum of its proper divisors (10202915953683).

21101222101221 is a wasteful number, since it uses less digits than its factorization.

21101222101221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1667221 (or 1667218 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21101222101221 its reverse (12210122210112), we get a palindrome (33311344311333).

The spelling of 21101222101221 in words is "twenty-one trillion, one hundred one billion, two hundred twenty-two million, one hundred one thousand, two hundred twenty-one".