primality
/praɪˈmælətɪ/the state of being primal (= relating to an early stage of development, or to the time when human life on earth began)
noun [抽象名词] 原始;首要;根本;素性
Of course, much more efficient algorithms for testing primality exist, but this one is the easiest to understand. 当然还有效率更高的素数测试方法,不过这种算法最容易理解。