Palindrome is a sentence that can be read forward and backward. It is a rhetorical device and word game in ancient and modern times, such as "I am for everyone and everyone is for me". In mathematics, there is also such a kind of numbers with such characteristics, called palindromes. ?

Let n be any natural number. If the natural number n 1 obtained by reversing the number of digits of n is equal to n, then n is called palindrome. For example, if n= 123432 1, then n is called a palindrome; But if n= 1234567, then n is not a palindrome.

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One of the characteristics of four-digit palindromes is that they will never be prime numbers. Assuming abba, it is equal to a *1000+b *100+b *10+a,10010b. Divisible by 1 1

With the help of electronic computer, it is found that the palindrome ratio of complete square number and complete cubic number is much larger than that of general natural number. For example,112 =1,22 2 = 484, 7 3 = 343,113 =133.

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