21200121221 has 2 divisors, whose sum is σ = 21200121222. Its totient is φ = 21200121220.

The previous prime is 21200121203. The next prime is 21200121253. The reversal of 21200121221 is 12212100212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16799788996 + 4400332225 = 129614^2 + 66335^2 .

It is a cyclic number.

It is not a de Polignac number, because 21200121221 - 2¹⁴ = 21200104837 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21200121196 and 21200121205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21200121421) 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 as a sum of consecutive naturals, namely, 10600060610 + 10600060611.

It is an arithmetic number, because the mean of its divisors is an integer number (10600060611).

Almost surely, 2^21200121221 is an apocalyptic number.

It is an amenable number.

21200121221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21200121221 is an equidigital number, since it uses as much as digits as its factorization.

21200121221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21200121221 its reverse (12212100212), we get a palindrome (33412221433).

The spelling of 21200121221 in words is "twenty-one billion, two hundred million, one hundred twenty-one thousand, two hundred twenty-one".