21013203221 has 2 divisors, whose sum is σ = 21013203222. Its totient is φ = 21013203220.

The previous prime is 21013203199. The next prime is 21013203301. The reversal of 21013203221 is 12230231012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15330154225 + 5683048996 = 123815^2 + 75386^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013203221 - 2⁶ = 21013203157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21013203221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21013203521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506601610 + 10506601611.

It is an arithmetic number, because the mean of its divisors is an integer number (10506601611).

Almost surely, 2^21013203221 is an apocalyptic number.

It is an amenable number.

21013203221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013203221 is an equidigital number, since it uses as much as digits as its factorization.

21013203221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21013203221 its reverse (12230231012), we get a palindrome (33243434233).

The spelling of 21013203221 in words is "twenty-one billion, thirteen million, two hundred three thousand, two hundred twenty-one".