66666643 has 2 divisors, whose sum is σ = 66666644. Its totient is φ = 66666642.

The previous prime is 66666631. The next prime is 66666653. The reversal of 66666643 is 34666666.

66666643 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66666643 - 2¹³ = 66658451 is a prime.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 66666643.

It is not a weakly prime, because it can be changed into another prime (66666653) 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, 33333321 + 33333322.

It is an arithmetic number, because the mean of its divisors is an integer number (33333322).

Almost surely, 2^66666643 is an apocalyptic number.

66666643 is a deficient number, since it is larger than the sum of its proper divisors (1).

66666643 is an equidigital number, since it uses as much as digits as its factorization.

66666643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 559872, while the sum is 43.

The square root of 66666643 is about 8164.9643599957. The cubic root of 66666643 is about 405.4800850564.

The spelling of 66666643 in words is "sixty-six million, six hundred sixty-six thousand, six hundred forty-three".