12643256321 has 2 divisors, whose sum is σ = 12643256322. Its totient is φ = 12643256320.

The previous prime is 12643256309. The next prime is 12643256323. The reversal of 12643256321 is 12365234621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12558340096 + 84916225 = 112064^2 + 9215^2 .

It is a cyclic number.

It is not a de Polignac number, because 12643256321 - 2²² = 12639062017 is a prime.

Together with 12643256323, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (12643256323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6321628160 + 6321628161.

It is an arithmetic number, because the mean of its divisors is an integer number (6321628161).

Almost surely, 2^12643256321 is an apocalyptic number.

It is an amenable number.

12643256321 is a deficient number, since it is larger than the sum of its proper divisors (1).

12643256321 is an equidigital number, since it uses as much as digits as its factorization.

12643256321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 35.

The spelling of 12643256321 in words is "twelve billion, six hundred forty-three million, two hundred fifty-six thousand, three hundred twenty-one".