I tried to find the answer on my own but was not sure if I knew where to look.
I went to wikipedia.org
I found "List of Democrat Party Superdelegates, 2016" (https://en.wikipedia.org/wiki/List_of_Democratic_Party_superdelegates,_2016)
It lists Hillary Clinton = 572-1/2
I found "Results of the 2016 Democratic Party presidential primaries" (https://en.wikipedia.org/wiki/Results_of_the_2016_Democratic_Party_presidential_primaries)
It reports that Hillary Clinton received 2,271 delegates in aggregate, with 571 being in excess of what she needed.
I could then conclude that she needed 571 of the 572.5 super-delegates to win the nomination.
However, this conflicts with your answer.
I am uncertain.