21000212221221 has 32 divisors (see below), whose sum is σ = 31182016896000. Its totient is φ = 13968399843504.

The previous prime is 21000212221207. The next prime is 21000212221223. The reversal of 21000212221221 is 12212221200012.

It is a happy number.

21000212221221 is a `hidden beast` number, since 2 + 10 + 0 + 0 + 212 + 221 + 221 = 666.

It is not a de Polignac number, because 21000212221221 - 2¹⁷ = 21000212090149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21000212221194 and 21000212221203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000212221223) 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, 30656070 + ... + 31333608.

It is an arithmetic number, because the mean of its divisors is an integer number (974438028000).

Almost surely, 2^{21000212221221} is an apocalyptic number.

It is an amenable number.

21000212221221 is a deficient number, since it is larger than the sum of its proper divisors (10181804674779).

21000212221221 is a wasteful number, since it uses less digits than its factorization.

21000212221221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680150 (or 680144 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21000212221221 its reverse (12212221200012), we get a palindrome (33212433421233).

The spelling of 21000212221221 in words is "twenty-one trillion, two hundred twelve million, two hundred twenty-one thousand, two hundred twenty-one".