Hi @hzh0005,
Your sequence counts are indeed very high, so you probably can follow @Emma_Dietrich's advice and choose 13,306 as your sampling depth (thank you @Emma_Dietrich for your answer!)
To give you a little more insight on how we usually choose a good sampling depth (particularly if we have lower sequencing counts), you can check out this tutorial. Alpha rarefaction plots indicate how sampling depth impacts alpha diversity (which will be tangentially related to impacts on beta diversity and other downstream analyses so is a good rough benchmark to use here). We are ideally looking for a sequencing depth at the point where these rarefaction curves begin to level off (indicating that most of the relevant diversity has been captured). This helps inform tough decisions that we need to make when some samples have lower sequence counts and we need to balance the priorities that @Emma_Dietrich summed up perfectly:
So give alpha rarefaction a try here — you will probably not need to use it, but it will be a good way to learn how to use this method to select sampling depths for future data sets.