247

This number is a composite.

+ This number has 47 elements in its Hailstone sequence (also known as the 3x + 1 sequence). [Patterson]

+ Digits sum to its smallest prime factor (247 = 13 x 19 and 2 + 4 + 7 = 13). [Hunter]

+ The sum of first 247 semiprimes yields another semiprime {98786}. Note that 247 is also a semiprime. [Bajpai]

+ The smallest 3-digit brilliant number whose prime factors, 13, 19, concatenated in both orders create primes, i.e., 1319, 1913. [Loungrides]

(There are 3 curios for this number that have not yet been approved by an editor.)

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