\[\boxed{\mathbf{445}.}\]
\[1)\ \sqrt[3]{64x^{3}z^{6}} =\]
\[= \sqrt[3]{64} \bullet \sqrt[3]{x^{3}} \bullet \sqrt[3]{z^{6}} =\]
\[= \sqrt[3]{4^{3}} \bullet x \bullet \sqrt[3]{z^{3 \bullet 2}} = 4xz^{2};\]
\[2)\ \sqrt[4]{a^{8}b^{12}} = \sqrt[4]{a^{8}} \bullet \sqrt[4]{b^{12}} =\]
\[= \sqrt[4]{a^{4 \bullet 2}} \bullet \sqrt[4]{b^{4 \bullet 3}} = a^{2}b^{3};\]
\[3)\ \sqrt[5]{32x^{10}y^{20}} =\]
\[= \sqrt[5]{32} \bullet \sqrt[5]{x^{10}} \bullet \sqrt[5]{y^{20}} =\]
\[= \sqrt[5]{2^{5}} \bullet \sqrt[5]{x^{5 \bullet 2}} \bullet \sqrt[5]{y^{5 \bullet 4}} = 2x^{2}y^{4};\]
\[4)\ \sqrt[6]{a^{12}b^{18}} = \sqrt[6]{a^{12}} \bullet \sqrt[6]{b^{18}} =\]
\[= \sqrt[6]{a^{6 \bullet 2}} \bullet \sqrt[6]{b^{6 \bullet 3}} = a^{2}b^{3}.\]