21304443221 has 2 divisors, whose sum is σ = 21304443222. Its totient is φ = 21304443220.

The previous prime is 21304443211. The next prime is 21304443229. The reversal of 21304443221 is 12234440312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19030202500 + 2274240721 = 137950^2 + 47689^2 .

It is a cyclic number.

It is not a de Polignac number, because 21304443221 - 2¹⁰ = 21304442197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21304443229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652221610 + 10652221611.

It is an arithmetic number, because the mean of its divisors is an integer number (10652221611).

Almost surely, 2^21304443221 is an apocalyptic number.

It is an amenable number.

21304443221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21304443221 is an equidigital number, since it uses as much as digits as its factorization.

21304443221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4608, while the sum is 26.

Adding to 21304443221 its reverse (12234440312), we get a palindrome (33538883533).

The spelling of 21304443221 in words is "twenty-one billion, three hundred four million, four hundred forty-three thousand, two hundred twenty-one".