In the first month, 10000 yuan was raised, in the second month, 1 (1+20%) million yuan was raised, in the third month, 1( 1+20%) million yuan was raised, …, and in the nth month.

1( 1+20%)n- 1 > 10，

1.2 n- 1> 10，

∵ 1.26× 1.27= 10.8> 10,

∴n- 1=6+7= 13，

n= 14，

So the answer is: 14.