75757...75757 (6249-digits)

This number is a prime.

7(57)_3124 = (75*10^6249-57)/99 is a palindromic prime containing the two largest possible smoothly undulating prime digits (i.e., 5 and 7). This number, also called smoothly undulating palindromic prime (SUPP), is the "sister" of 3(23)_3479 = (32*10^6959-23)/99. [Rosenthal and Martin]