using namespace std;
bool primzahl(unsigned long long zahl)
{
for(unsigned long long j = 2; j*2<zahl;j++)
{
	if (zahl%j == 0)
	{
		return false;
	}
}
return true;
}

int main ()
{
unsigned long long a = 317584931803;
for(unsigned long long i = 2; i <a/2;i++){
	if(a%i == 0){
		if(primzahl(i)){
			cout << i <<endl;
	}
}
}
}


Die Fehlermeldung:
3.cpp:18: error: integer constant is too large for 'long' type