11,21,23,29,31,37,41,43,51,61,71,79,91,97中哪些是素数,哪些是合数
问题描述：
11,21,23,29,31,37,41,43,51,61,71,79,91,97中哪些是素数,哪些是合数
答
11,23,29,31,37,41,43,61,71,91,97是素数,
21,51是合数