77498...89477 (715-digits)

This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).


2
3002003
3043002003403
3063043002003403603
3533063043002003403603353
3063533063043002003403603353603
1513063533063043002003403603353603151
3111513063533063043002003403603353603151113
3183111513063533063043002003403603353603151113813
3273183111513063533063043002003403603353603151113813723
3043273183111513063533063043002003403603353603151113813723403
3093043273183111513063533063043002003403603353603151113813723403903
3393093043273183111513063533063043002003403603353603151113813723403903933
3653393093043273183111513063533063043002003403603353603151113813723403903933563
1003653393093043273183111513063533063043002003403603353603151113813723403903933563001
3231003653393093043273183111513063533063043002003403603353603151113813723403903933563001323
1683231003653393093043273183111513063533063043002003403603353603151113813723403903933563001323861
3301683231003653393093043273183111513063533063043002003403603353603151113813723403903933563001323861033
3153301683231003653393093043273183111513063533063043002003403603353603151113813723403903933563001323861033513
9093153301683231003653393093043273183111513063533063043002003403603353603151113813723403903933563001323861033513909
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Above is one-sixth of a palindromic prime pyramid (starting at 2) of step size 3 with record-breaking height 120 that ends with a 715-digit palindromic prime. It was found by Michael Branicky and first reported at Carlos Rivera's "Prime Puzzles & Problems Connection" website on September 22, 2023.