643666579 has 2 divisors, whose sum is σ = 643666580. Its totient is φ = 643666578.

The previous prime is 643666561. The next prime is 643666619. The reversal of 643666579 is 975666346.

643666579 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643666579 - 2⁷ = 643666451 is a prime.

It is not a weakly prime, because it can be changed into another prime (643666549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321833289 + 321833290.

It is an arithmetic number, because the mean of its divisors is an integer number (321833290).

Almost surely, 2^643666579 is an apocalyptic number.

643666579 is a deficient number, since it is larger than the sum of its proper divisors (1).

643666579 is an equidigital number, since it uses as much as digits as its factorization.

643666579 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 52.

The square root of 643666579 is about 25370.5849163948. The cubic root of 643666579 is about 863.4164525781.

The spelling of 643666579 in words is "six hundred forty-three million, six hundred sixty-six thousand, five hundred seventy-nine".