H.C.F of 4 x 27 x 3125, 8 x 9 x 25 x 7 and 16 x 81 x 5 x 11 x 49 is :

4 x 27 x 3125 =  $22 \times 33 \times 55$ ;

8 x 9 x 25 x 7 =  $23 \times 32 \times 52 \times 7$

16 x 81 x 5 x 11 x 49 =  $24 \times 34 \times 5 \times 11 \times 72$

H.C.F = $22 \times 32 \times 5$ = 180.