\[\boxed{\mathbf{269}.}\]
\[1)\ a = 25^{10} + 7 \cdot 5^{18};\ \ m = 32:\]
\[a = \left( 5^{2} \right)^{10} + 7 \cdot 5^{18} = 5^{20} +\]
\[+ 7 \cdot 5^{18} = 5^{18} \cdot \left( 5^{2} + 7 \right) =\]
\[= 5^{18} \cdot 32\ \vdots 32.\]
\[2)\ a = 10^{15} + 10^{20} - 92;\ \ \]
\[m = 18.\]
\[a = 10^{15} - 1 + 10^{20} - 1 - \underset{\vdots 18}{\overset{90}{︸}};\]
\[\left( \left( 10^{5} \right)^{3} - 1 \right) +\]
\[+ \left( 10^{10} - 1 \right)\left( 10^{10} + 1 \right) =\]
\[= \left( 10^{5} - 1 \right)\left( 10^{10} + 10^{5} + 1 \right) +\]
\[+ \left( 10^{5} - 1 \right)\left( 10^{5} + 1 \right) \cdot\]
\[\cdot \left( 10^{10} + 1 \right) =\]