Multiplying prime numbers If I multiply $13$ and $17$ to get $221$ I can only get $221$ by multiplying $13$ and $17$ (excluding $1$ and $221$) does the same rule apply to multiplying $3$ numbers? (excluding the use of $1$)

So you have two distinct positive primes, let's call them $p$ and $q$. Then their product has precisely four divisors among the positive integers: 1, $p$, $q$ and $pq$ itself, and we verify that $1 \times pq = pq$.
In your example with $p = 13$ and $q = 17$ (or $p = 17$ and $q = 13$, if you prefer), we verify that $1 \times 221 = 13 \times 17$.
What if we throw a third distinct positive prime, $r$, into the mix? Then $pqr$ has eight divisors: 1, $p$, $q$, $r$, $pq$, $pr$, $qr$ and $pqr$ itself.
To expand on the previous example, let's say $r = 29$. Then we see that 6409 can be expressed as a product of two positive integers four different ways: $$1 \times 6409 = 13 \times 493 = 17 \times 377 = 29 \times 221$$ But none of those ways consist of two primes, because the number is the product of three primes.
