To simplify \((19^4)^9\) using the Power Rule of Exponents, which states that \((a^m)^n = a^{m \cdot n}\), you multiply the exponents.
Here, \(m = 4\) and \(n = 9\):
\[ (19^4)^9 = 19^{4 \cdot 9} = 19^{36} \]
So, the simplified equivalent expression is:
\[ 19^{36} \]