In order to count the number of stars there, properly, you have to work out what area, in terms of light years, the piccie covers, then multiply that by the distance to M22. That gives you the volume in cubic light years. You then multiply that by the average density of stars per cubic light year (for the galaxy as a whole). That'll give a reasonable estimate of how many stars there are there, including those you can't see, up to the distance M22 lies at
Then add 750000 for M22 itself