646, Much of what the Greeks got right, they got from us. This is as clear as day. See what Rav Chaim Kanievsky points out in Kiryas Melech (Yesodei Hatorah 3:1).
Here’s how this works: The Rishonim will quote something from the Greek philosophers but which really comes from Kabbalah. They do this because when citing Kabalistic ideas, they often try to conceal them as much as possible. Therefore, if something is well known as a Greek philosophical concept, they will quote it as such even though its source is Judaism. Example: The Ramban’s hyly (hiuli?) at the beginning of Bereishis, which he notes and sources as Greek. Both the Satmar Rebbe (Divrei Yoel Bereishis p.61) and Rav Elya Lopian (quoted by Rav Scwardron) say the hyly is a Kabbalistic, spiritual idea, which the Greeks took from us. The Divrei Yoel explains that the Ramban quoted this in the name of the Greeks because it is the derech of the Ramban to camouphlage such sodos in physical terms – the same as Chazal often did. (see also Rama Toras HaOlah on Boruch Sheamar). Another one of these concepts is the 4 elements (fire, waster, air, and earth), which is quoted all over by the Greeks but comes from Kabbalah – they took it from us.
The idea that the Greeks took their philosophical ideas from us is all over the Rishonim and Achronim, including the Ramban himself (Toras Hashem Temimah p.162). He says that they lifted their knowledge from the Jews, and eventually it got distorted by them. But the source is Judaism. The Kuzari says the same thing (2:66 – see also 2:19 and 1:62) as does the Shevili Emunah (nesiv 8) the Rama (he brings that Socrates got his wisdom from Asaf and Achitofel (Toras Haolah 1:12), and Chosid Yaavetz (Ohr Hachaim 6). The Chida (Midbar Kadmos – Sheva Chachmos) says this in the name of the Rambam (se alos Moreh Nevuchim 1:71).
Basically what happened was, people like Shlomo HaMelech and the Neviim had this chachma, the Greek philosophers such as Plato and Aristotle learned from them, we went into Golus and a lot of it got lost, while among the Greeks it got grotesquely distorted. So youll find Torah and Kabbalistic concepts among the Goyim but kind of in a messed up way. Sometimes Rishonim such as the Ramban will identify some crumb of truth among them that comes from us and he will quote it from them if it is known as such.
Regarding Ptolmey himself, the Abarbanel (Shmos 12) quotes Ptolmey as being so impressed with the Jews’ astronomical calculations, that he said it proves the Jews had prophecy. In the Sefer Eretz Zvi (by Rav Aryeh Zvi Fromer ZTL, Rosh Yeshiva in Chachmei Lublin), quotes more such sources about Ptolmey.