21002100221221 has 48 divisors (see below), whose sum is σ = 25627910039424. Its totient is φ = 17128183180416.

The previous prime is 21002100221171. The next prime is 21002100221233. The reversal of 21002100221221 is 12212200120012.

It is a happy number.

It is not a de Polignac number, because 21002100221221 - 2²⁷ = 21001966003493 is a prime.

It is a super-2 number, since 2×21002100221221² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21002100221195 and 21002100221204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002100222221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2116502166 + ... + 2116512088.

It is an arithmetic number, because the mean of its divisors is an integer number (533914792488).

Almost surely, 2^{21002100221221} is an apocalyptic number.

It is an amenable number.

21002100221221 is a deficient number, since it is larger than the sum of its proper divisors (4625809818203).

21002100221221 is a wasteful number, since it uses less digits than its factorization.

21002100221221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19690 (or 19683 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21002100221221 its reverse (12212200120012), we get a palindrome (33214300341233).

The spelling of 21002100221221 in words is "twenty-one trillion, two billion, one hundred million, two hundred twenty-one thousand, two hundred twenty-one".