It is a prime factorization because each base (2,3,5, and 11) is a prime number.
A prime number is one where the only factors of it are 1 and itself.
factors of 2 = 1 and 2
factors of 3 = 1 and 3
factors of 5 = 1 and 5
factors of 11 = 1 and 11
Instead of saying something like 11^2, we could write 11*11. Similarly, 5^4 could be written as 5*5*5*5. Though it's a good idea to use exponents so you make the prime factorization more compact and save time.
The '3' without an exponent is the same as 3^1. You'll often see that exponent of 1 left out. Again this is to save time.
