Each composite number has its own unique prime factorization. The largest number in that factorization would be the largest prime factor. It will never be more than half of the original number.
71
7 is the greatest prime factor of 84.
The greatest prime factor they have in common is 2.
The prime factorization of 99999 is 3 x 3 x 41 x 271
The prime number is the prime factorization. For example, the prime factorization of the prime number 3 is 3. Get it?
The prime factorization of 8500 is 2 x 2 x 5 x 5 x 5 x 17. If listed in numerical order from smallest to largest, the last number in the prime factorization is 17.
99,999=3x3x41x271
43/7 = 6.142857
53 is a prime number so there is no relevant prime factorization for it.
The only number with that prime factorization has to be 48.
91 cannot be in the prime factorization of any number because it is not a prime number itself.