\[\boxed{\text{443\ (443).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ 2^{20} = \left( 2^{2} \right)^{10}\]
\[\textbf{б)}\ \ 2^{20} = \left( 2^{4} \right)^{5}\]
\[\textbf{в)}\ \ 2^{20} = \left( 2^{5} \right)^{4}\]
\[\textbf{г)}\ \ 2^{20} = \left( 2^{10} \right)^{2}\]