6561275321 has 2 divisors, whose sum is σ = 6561275322. Its totient is φ = 6561275320.

The previous prime is 6561275299. The next prime is 6561275381. The reversal of 6561275321 is 1235721656.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6535914025 + 25361296 = 80845^2 + 5036^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561275321 - 2¹⁰ = 6561274297 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (6561275381) 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, 3280637660 + 3280637661.

It is an arithmetic number, because the mean of its divisors is an integer number (3280637661).

Almost surely, 2^6561275321 is an apocalyptic number.

It is an amenable number.

6561275321 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561275321 is an equidigital number, since it uses as much as digits as its factorization.

6561275321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75600, while the sum is 38.

The square root of 6561275321 is about 81001.6994945168. The cubic root of 6561275321 is about 1872.1016265148.

Adding to 6561275321 its reverse (1235721656), we get a palindrome (7796996977).

The spelling of 6561275321 in words is "six billion, five hundred sixty-one million, two hundred seventy-five thousand, three hundred twenty-one".