I am still counting but here are here are sum of the number references I've figured out so far.

In Harry's world four is not a very lucky number. Right of the bat there's Number 4 Privet Drive where Harry lives not a happy life with Uncle Vernon, Aunt Petunia, and of course, Dudley. Here are a few more four-boding examples: Harry became the unlikely and unexpected fourth champion in the Tri-Wizard Tournament; he was fourth and last to draw his dragon, the Hungarian Horntail, arguably the most vicious of the dragons to face, out of the bag; Harry's watch stopped working in his fourth year... suggesting one phase of his life has ended and another is about to begin... as well as suggesting that time has once more stopped, suspended, until Voldemort's return; Harry's fourth year at Hogwarts he not only faced dragons but witnessed the return of Lord Voldemort and had to face the dark lord in a real battle for his life; Wormtail was the fourth member of the band of school pals which included James, Remus, and Sirius. Is Jo hinting there is a four-gone conclusion to this tale?

Seven also is used again and again:  The Gryffindors are on the 7th floor, as is the Room of Necessity; there are 7 Players on a Quidditch Team; there are; there are 7 Weasley children; it takes 7 years to complete Hogwarts Training; there are 7 bottles of potion in the PS/SS; Gilderoy wrote 7 books; there are 7 registered animagi; Harry’s birthday is July, the 7th month.

Among the several references to the number “11” is the fact that both Harry and his father’s wands are 11 inches length.

If you count Harry and Hermione as part of the Weasley family then there are 11 members, and it’s obvious that Molly does consider Harry her other son, and probably Hermione as her other daughter.

In POA Harry stays in Room 11 at the Leaky Cauldron.  The Hogwarts Express leaves London at exactly 11:00 AM.  There are several more time, place, and things equaling eleven throughout the series.

Twelve is used again and again throughout the series.  Once again there is a 12th hour feel.

Examples in:  12 Streetlights on Privet Drive; 12 O.W.L.S; 12 Blast-Ended Skrewts; Time and Date References; Chapter 12 in each book is a significant chapter.  (Also chapters 7, 11, and 13); 12 doors in the Dept. of Mysteries; Wormtail killed 12 muggles then faked his own death and went underground for 12 years; etc.  Sirius is in Azkaban for 12 years; Aunt Marge has 12 bulldogs.

Harry’s birthday is on the 31st, which is 13 backwards.

Sirius Black is accused of killing 13 people including Peter Pettigrew; Voldemort rises again after 13 years.

Bad luck people and events seem to happen in all HP Chapter Thirteens.