9973

+ The largest prime less than ten thousand; additionally, on deleting the last digit, it becomes the largest prime less than one thousand. [Hasler]

+ The largest 4-digit prime whose sum of digits is a perfect number. [Loungrides]

+ The only 4-digit prime formed from the concatenation of two primes summed to a thousand, (997, 3). [Loungrides]

(There are 2 curios for this number that have not yet been approved by an editor.)

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