What is 2^2.1, and why?

how do you work out 2 to the power of 2.1?, do i do 2.1 * 2.1, or 2.1 *2

$\begin{array}{rcll} 2^{2.1} &=& 2^{2+0.1} \\ &=& 2^2\cdot 2^{0.1} \\ &=& 4\cdot 2^{0.1} \\ &=& 4\cdot 2^{\frac{1}{10}} \\ &=& 4\cdot \sqrt[10]{2} \\ &=& 4\cdot 1.07177346254 \\ &=& 4.28709385015 \\ \end{array}$