Insert a certain text to pdfs without opening the pdfs

Dear

i'm looking for a solution that can help me.

example: I have 7 pdf files, each pdf file containts minimum 1 page.

I want to have e number on the first page : 201700001 , but then it should count +1 for every next pdf file.

the flenames of the pdf files should be the starter point to know which pdf is next to give it that number in the first page.

preferable middle top side , not to small.

now I'm doing this by:

opening pdf

go to tools
insert and sign

the icon |Ab I insert it in the top middle document

I click twice on A to enlarge the text

then I typ manually the number: 201700064

hit tab, then save (save as, select folder, click to confirm  replace original one) document and close it.

then next: same steps, this get number 201700065...

....

would be geat to be able to automate this. as there are many steps to do to get this little result.

I use Adobe Acrobat reader DC version 2018.009.20044  ( free version). if there is a paid version that can do it, please informe me about it.