Erdos wasn't out of the ordinary because he published with (read: collaborated with) so many coauthors. He was out of the ordinary because he published so many papers, period. His sociability was more of a difference of degree within mathematics, not category.

I beg to differ. Anecdotes of Erdos' itinerant lifestyle are legendary in the field:

> Dr. Erdos traveled from meeting to meeting, carrying a half-empty suitcase and staying with mathematicians wherever he went. His colleagues took care of him, lending him money, feeding him, buying him clothes and even doing his taxes. In return, he showered them with ideas and challenges -- with problems to be solved and brilliant ways of attacking them. (https://www.nytimes.com/1996/09/24/us/paul-erdos-83-a-wayfar...)

Even in the rarefied club of oddball math personalities, he stood out.

Ah, by sociability I just meant the number of collaborators he worked with. What I'm getting at is that he's abnormal because he published so much, not because he published with so many coauthors. Many mathematicians would have similar looking publication records if they maintained the same level of collaboration and simply published...more.

But he was an oddball too, for sure.