21210304321 has 2 divisors, whose sum is σ = 21210304322. Its totient is φ = 21210304320.

The previous prime is 21210304267. The next prime is 21210304343. The reversal of 21210304321 is 12340301212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20816718400 + 393585921 = 144280^2 + 19839^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21210304321 is a prime.

It is a super-3 number, since 3×21210304321³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21210304361) 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, 10605152160 + 10605152161.

It is an arithmetic number, because the mean of its divisors is an integer number (10605152161).

Almost surely, 2^21210304321 is an apocalyptic number.

It is an amenable number.

21210304321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210304321 is an equidigital number, since it uses as much as digits as its factorization.

21210304321 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21210304321 its reverse (12340301212), we get a palindrome (33550605533).

The spelling of 21210304321 in words is "twenty-one billion, two hundred ten million, three hundred four thousand, three hundred twenty-one".