What is the least prime number used by students?

Could you please clarify what you mean by "the least prime number used by students"? Are you referring to a specific context, such as in mathematics education or cryptography courses? Prime numbers are natural numbers greater than 1 that have no positive divisors other than 1 and themselves. The smallest prime number is 2, but it's unclear if you're asking about a specific application or scenario where students might use a particular prime number. Could you provide more context or elaborate on your question?