- Difficulty: Medium
- Tags: LeetCode, Medium, Math, Number Theory, leetcode-866, O(n^(1/2) * (logn + n^(1/2))), O(logn)
Problem
Given an integer n, return the smallest prime palindrome greater than or equal to n.
An integer is prime if it has exactly two divisors: 1 and itself. Note that 1 is not a prime number.
- For example,
2,3,5,7,11, and13are all primes.
An integer is a palindrome if it reads the same from left to right as it does from right to left.
- For example,
101and12321are palindromes.
The test cases are generated so that the answer always exists and is in the range [2, 2 * 108].
Example 1:
Input: n = 6 Output: 7
Example 2:
Input: n = 8 Output: 11
Example 3:
Input: n = 13 Output: 101
Constraints:
1 <= n <= 108