一个数只有1和它本身两个约数,这样的数叫作质数(也叫素数)。一、节日质数61,71,101二、回文质数有些质数不管是从左往右读,还是从右往左读,读出的结果都相同,这样的质数叫作“回文质数”。例如,131,151,181,191,313……三、正倒质数13→31,79→97,157→751,1231→1321 A number is only 1 and itself two divisors, such number is called prime (also known as prime). First, the festival prime 61,71,101 Second, the quality of the backdating Some prime Whether it is read from left to right, or read from right to left, read out the results are the same, this prime number is called For example, 131,151,181,191,313 ... ... three positive prime 13 → 31,79 → 97,157 → 751,1231 → 1321