1289

This number is a prime.

+ This Sophie Germain prime is also a twin prime, and the smallest prime having distinct or increasing digits and exactly 5 permutations of its digits prime. [Hasler]

+ Concatenate (left-to-right) the 1st, 2nd, 8th, and 9th prime and you will get another prime, i.e., 231923. [Loungrides]

+ Smallest four-digit prime number for which the product of each digit is the square of the first two digits. [Deshpande]

+ On an infinite spiral-numbered chessboard, if a queen starts from 1 (centre of the spiral) and repeatedly moves to the nearest unvisited prime-numbered square, then eventually the queen can no longer move after, at square number 1289. [Gudipati]

(There are 8 curios for this number that have not yet been approved by an editor.)

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