21201201221 has 2 divisors, whose sum is σ = 21201201222. Its totient is φ = 21201201220.

The previous prime is 21201201199. The next prime is 21201201233. The reversal of 21201201221 is 12210210212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20341890625 + 859310596 = 142625^2 + 29314^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201201221 - 2³⁰ = 20127459397 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21201201196 and 21201201205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201201271) 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, 10600600610 + 10600600611.

It is an arithmetic number, because the mean of its divisors is an integer number (10600600611).

Almost surely, 2^21201201221 is an apocalyptic number.

It is an amenable number.

21201201221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201201221 is an equidigital number, since it uses as much as digits as its factorization.

21201201221 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 21201201221 its reverse (12210210212), we get a palindrome (33411411433).

The spelling of 21201201221 in words is "twenty-one billion, two hundred one million, two hundred one thousand, two hundred twenty-one".