Well, some of them are required to manage the others. Those managers need secretaries. Some of them are required to prepare reports for the managers. Some of them provide HR support for such a large workforce. Also, you need IT support for all those secretaries, report-generators, managers, and HR people. Payroll department needs to be larger given how many people work there. I could go on, but I think you get the idea.
I work at a warehouse with ~300 employees, selling over 70,000 different skus, etc. We have 3 Programmers, and 3 IT/network people, 1 hr, etc. We're hiring more programmers though.
What the heck are 360+ employees doing? You're right you do need lots of management, but there's no way they need that many people. Like, thats a LOT of people.