21213320221 has 2 divisors, whose sum is σ = 21213320222. Its totient is φ = 21213320220.

The previous prime is 21213320209. The next prime is 21213320237. The reversal of 21213320221 is 12202331212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19877052196 + 1336268025 = 140986^2 + 36555^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213320221 - 2²⁹ = 20676449309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213320291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606660110 + 10606660111.

It is an arithmetic number, because the mean of its divisors is an integer number (10606660111).

Almost surely, 2^21213320221 is an apocalyptic number.

It is an amenable number.

21213320221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213320221 is an equidigital number, since it uses as much as digits as its factorization.

21213320221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21213320221 its reverse (12202331212), we get a palindrome (33415651433).

The spelling of 21213320221 in words is "twenty-one billion, two hundred thirteen million, three hundred twenty thousand, two hundred twenty-one".