Ninja Boy: Saru

You enter the village, which appears to be empty, and look around for your client.  Where is the ninja boy?  As you search the streets, a quick movement catches your eye.

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A young boy appears in front of you, with two monkeys hanging off his arm and shoulder.  He greets you with a smile and excitedly says:

"Hi, are you the GOM agent that is going to help me?  I'm so glad you could make it.  My name is Saru, and I really need your help in this mission of mine!"

You listen to Saru and find out the following:

Saru and his monkeys have a mission to deliver 539 bottles of medicine to a village.  The bottles of medicine are packed into baskets.  Each basket can hold 21 bottles of medicine.  About how many baskets will Saru and his monkeys have to deliver?