Step 1: Prime factorization of 144.
First, factorize 144:
\[
144 \div 2 = 72 \quad \Rightarrow \quad 72 \div 2 = 36 \quad \Rightarrow \quad 36 \div 2 = 18 \quad \Rightarrow \quad 18 \div 2 = 9
\]
\[
9 \div 3 = 3 \quad \Rightarrow \quad 3 \div 3 = 1
\]
So, the prime factorization of 144 is:
\[
144 = 2^4 \times 3^2
\]
Step 2: Find the sum of the powers of the prime factors.
The powers of the prime factors are $4$ for $2$ and $2$ for $3$.
The sum of these powers is:
\[
4 + 2 = 6
\]
Step 3: Conclusion.
Therefore, the sum of powers of prime factors of 144 is $6$.