A small explanation: This is not the total Merit number that is generated every month, but the number of sMerits obtained by the merit sources. If they spend the entire amount, there are 21045/2 new sMerits to be spent.
Also, if Merit sources do not spend their sMerits, they will not get more, but the amount that has been spent will be refilled during the month, meaning that if you do not spend any sMerit, the total will be your source of merit.