21212100121221 has 16 divisors (see below), whose sum is σ = 31448089059520. Its totient is φ = 14131160084880.

The previous prime is 21212100121139. The next prime is 21212100121243. The reversal of 21212100121221 is 12212100121212.

21212100121221 is a `hidden beast` number, since 212 + 1 + 210 + 0 + 1 + 21 + 221 = 666.

It is not a de Polignac number, because 21212100121221 - 2¹¹ = 21212100119173 is a prime.

It is a super-3 number, since 3×21212100121221³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212100121194 and 21212100121203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212100121271) 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, 284406355 + ... + 284480928.

It is an arithmetic number, because the mean of its divisors is an integer number (1965505566220).

Almost surely, 2^{21212100121221} is an apocalyptic number.

It is an amenable number.

21212100121221 is a deficient number, since it is larger than the sum of its proper divisors (10235988938299).

21212100121221 is a wasteful number, since it uses less digits than its factorization.

21212100121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 568888673 (or 568888667 counting only the distinct ones).

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

Adding to 21212100121221 its reverse (12212100121212), we get a palindrome (33424200242433).

Subtracting from 21212100121221 its reverse (12212100121212), we obtain a palindrome (9000000000009).

The spelling of 21212100121221 in words is "twenty-one trillion, two hundred twelve billion, one hundred million, one hundred twenty-one thousand, two hundred twenty-one".