21234201221 has 2 divisors, whose sum is σ = 21234201222. Its totient is φ = 21234201220.

The previous prime is 21234201193. The next prime is 21234201269. The reversal of 21234201221 is 12210243212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14044857121 + 7189344100 = 118511^2 + 84790^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21234201221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21234201193 and 21234201202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21234206221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10617100610 + 10617100611.

It is an arithmetic number, because the mean of its divisors is an integer number (10617100611).

Almost surely, 2^21234201221 is an apocalyptic number.

It is an amenable number.

21234201221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21234201221 is an equidigital number, since it uses as much as digits as its factorization.

21234201221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21234201221 its reverse (12210243212), we get a palindrome (33444444433).

The spelling of 21234201221 in words is "twenty-one billion, two hundred thirty-four million, two hundred one thousand, two hundred twenty-one".