What's the suggested architecture to process millions of documents per hour?

Is there any model architecture for the MongoDB Shard cluster that needs to process millions of documents per hour? Also, How can I define the number of Config Servers, Mongos (Routers), and Shards (Primary and Replicas) for my MongoDB Shard cluster?

The minimum is

  1. A replica set of 3 config servers
  2. 3 servers for each shards
  3. A minimum of 2 mongos servers.