[求助]prep一题，讨论贴中没有

spritejudy

the positive integer k has exactly two positive prime factors, 3 and 7. If k has a total of 6 positive factors, including 1 and k, what is the value of k?

1) 3^2 is a factor of k

2) 7^2 is not a factor of k

answer: D

pippipeng

它可以是3x3x7 或者3x7x7.