6666305742721 has 2 divisors, whose sum is σ = 6666305742722. Its totient is φ = 6666305742720.

The previous prime is 6666305742671. The next prime is 6666305742727. The reversal of 6666305742721 is 1272475036666.

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., 5733922382721 + 932383360000 = 2394561^2 + 965600^2 .

It is a cyclic number.

It is not a de Polignac number, because 6666305742721 - 2¹¹ = 6666305740673 is a prime.

It is not a weakly prime, because it can be changed into another prime (6666305742727) 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, 3333152871360 + 3333152871361.

It is an arithmetic number, because the mean of its divisors is an integer number (3333152871361).

Almost surely, 2^{6666305742721} is an apocalyptic number.

It is an amenable number.

6666305742721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6666305742721 is an equidigital number, since it uses as much as digits as its factorization.

6666305742721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15240960, while the sum is 55.

The spelling of 6666305742721 in words is "six trillion, six hundred sixty-six billion, three hundred five million, seven hundred forty-two thousand, seven hundred twenty-one".