Mine has been at 26 since the forum switched over, I think it's just an arbitrary number at this point!
Hover the cursor over your name in the top navigation bar. From the drop down menu that appears click "Notifications".
Once you're on the notification page, you'll notice there are two choices:
(1) Settings (2) Primary Notifications
The settings page has 3 boxes, the primary notifications page has 17 boxes.
Try unchecking all 20 boxes. Go back to the forums directory page and see if the number clears. You may have to refresh the page. Afterwards you'll have to go back to the notifications pages and re-check the boxes for the things you want to be notified about … and how you want to be notified.
There are also boxes on the "Personal Settings" page you may try unchecking.