6668778643 has 2 divisors, whose sum is σ = 6668778644. Its totient is φ = 6668778642.

The previous prime is 6668778637. The next prime is 6668778667. The reversal of 6668778643 is 3468778666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6668778643 - 2¹⁷ = 6668647571 is a prime.

It is not a weakly prime, because it can be changed into another prime (6668728643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3334389321 + 3334389322.

It is an arithmetic number, because the mean of its divisors is an integer number (3334389322).

Almost surely, 2^6668778643 is an apocalyptic number.

6668778643 is a deficient number, since it is larger than the sum of its proper divisors (1).

6668778643 is an equidigital number, since it uses as much as digits as its factorization.

6668778643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48771072, while the sum is 61.

The square root of 6668778643 is about 81662.5902295537. The cubic root of 6668778643 is about 1882.2707813607.

The spelling of 6668778643 in words is "six billion, six hundred sixty-eight million, seven hundred seventy-eight thousand, six hundred forty-three".