Let us convert the given number in words into numerals as follows:

Eleven lakh$=11,00,000$

Seventy thousand$=70,000$

Six hunderd$=600$

Seven$=7$

Now, add the numerals as shown below:

$1100000+70000+600+7=1170607$

Therefore, the required number is $11,70,607$.

Hence, the missing digit in $11,70,\_07$ is $6$.