643870679 has 2 divisors, whose sum is σ = 643870680. Its totient is φ = 643870678.

The previous prime is 643870637. The next prime is 643870751. The reversal of 643870679 is 976078346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643870679 - 2²⁸ = 375435223 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643870079) 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, 321935339 + 321935340.

It is an arithmetic number, because the mean of its divisors is an integer number (321935340).

Almost surely, 2^643870679 is an apocalyptic number.

643870679 is a deficient number, since it is larger than the sum of its proper divisors (1).

643870679 is an equidigital number, since it uses as much as digits as its factorization.

643870679 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1524096, while the sum is 50.

The square root of 643870679 is about 25374.6069723257. The cubic root of 643870679 is about 863.5077030696.

The spelling of 643870679 in words is "six hundred forty-three million, eight hundred seventy thousand, six hundred seventy-nine".