643591859 has 2 divisors, whose sum is σ = 643591860. Its totient is φ = 643591858.

The previous prime is 643591853. The next prime is 643591873. The reversal of 643591859 is 958195346.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643591859 - 2⁴ = 643591843 is a prime.

It is not a weakly prime, because it can be changed into another prime (643591853) 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, 321795929 + 321795930.

It is an arithmetic number, because the mean of its divisors is an integer number (321795930).

Almost surely, 2^643591859 is an apocalyptic number.

643591859 is a deficient number, since it is larger than the sum of its proper divisors (1).

643591859 is an equidigital number, since it uses as much as digits as its factorization.

643591859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1166400, while the sum is 50.

The square root of 643591859 is about 25369.1123021678. The cubic root of 643591859 is about 863.3830414011.

The spelling of 643591859 in words is "six hundred forty-three million, five hundred ninety-one thousand, eight hundred fifty-nine".