what is the greatest prime you must consider to test whether 4178 is a prime?

Mmmh, since 4178 is even, it clearly cannot be prime.

The largest prime I had to consider was 2 as a divisor, and since 4178 is divisible by 2, it is not a prime

the greatest possible factor of N is √N.

If there is a factor bigger than √N, then it means there is another less than √N. But if you've tried all the primes up to √N, you'd already have found it.

So, find the largest prime less than √4178 = 64.6
That would be 61

To determine whether the number 4178 is a prime number, you need to find the greatest prime number that you should consider when testing its primality.

To do this, you can start by finding the square root of 4178. The square root of 4178 is approximately 64.635.

Now, you need to check for any prime numbers less than or equal to 64.635. By checking if 4178 is divisible by any of these prime numbers, you can determine if it is prime.

To find the greatest prime number less than or equal to 64.635, you can generate a list of prime numbers and check them one by one. This can be done using various algorithms, such as the Sieve of Eratosthenes or checking divisibility of numbers up to the square root.

Alternatively, you can use a pre-generated list of prime numbers and search for the greatest one that is less than or equal to 64.635. There are several online resources and prime number calculators available that provide lists of prime numbers up to a certain range, or you can use mathematical software such as MATLAB or Python with prime number libraries to generate the list.

By performing this search, you will find that the greatest prime number less than or equal to 64.635 is 61. Therefore, 61 is the greatest prime number you need to consider when testing whether 4178 is a prime number.