Some online sources list a run of 611 performances. That seems almost certainly to be incorrect. At the time of the closing, the New York Times and the New York Herald Tribune listed 520, while the Daily News and The Billboard (as it was then known) listed 521.
It’s possible that neither is exactly correct. The production opened on a Wednesday evening. It ran 65 weeks, if you count the first week as a whole week. In the past, it seems that sometimes performance totals listed at the end of a run were simply the number of weeks a show had played times eight, even when a show had not played eight performances during its first week. In this case, 65 weeks times 8 would equal 520, but the production would seem to have played only five performances during its first week. There may have been a couple of previews. We are listing 517 performances, basing that on 64 weeks of eight performances a week, and one week of five performances. It may be impossible at this time to determine exactly how many performances the production played.