Obviously, if the number of people exceeds 1, then the tables for 3, 5, 7 and 9 people will be full. At this time, the number of people is the common multiple of 3, 5, 7 and 9.

Least common multiple = 5*7*9 = 3 15

Then we know that the primitive number = 3 15K- 1 can be divisible by 1 1.

315k-1= 28 * 1 1 k+7k-1divisible by11,that is,

7K- 1 is divisible by 1 1, then the enumeration method k is at least 8.

There are at least 315 * 8-1= 2519 people in the room.

5*7*9* 1 1=3465, so the number may be 3465P+25 19.