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Concatenating prime factors One day I was bored and started concatenating natural numbers.When I reached 7 I got more bored and started even to calculate its prime factors. So I got 1234567 = 127 x 9721 and looked at it for a few minutes. My boredom paid off because suddenly I discovered a palindrome. Just concatenate the two prime factors and there it is 1279721. Boredom now completely turned into exitement especially when I calculated the difference between these two seven-digit numbers : 1279721 – 1234567 = 45154 I don't need to tell you what kind of a number that is, do I ?  Here is a spin-off from the above explained construction. 14432823441 = 3 x 3 x 281 x 313 x 18233 = 3328131318233 after concatenation of the prime factors. I leave it up to you to post me larger palindromic solutions !  Please, consult also the following integer sequences from Sloane's database !  A046447 A046448 A046449 A046450 [ June 2001 ] Terry Trotter (†)(email) from El Salvador (homepage) discovered that the prime factors of the concatenation of 127 and 9721 or 1279721 are all three emirps (79 x 97 x 167) which upon concatenation form yet another prime namely 7997167. (Prime Curios 1234567) | |||
 A000048 Prime Curios! Prime Puzzle Wikipedia 48 Le Nombre 48 Numberland 48 | |||
