Thank you MOFI. this worked. Here is the answer, for who needs it in the future:
echo !currPdfName!| %SystemRoot%\System32\findstr.exe /I /R "^[12][09][01234-9][01234-9][01][01234-9][0123][01234-9][01234-9][01234-9]*[01234-9][01234-9]*_[01234-9].pdf$"