65531...81761 (25-digits)

This number is a composite.

                                                 65531 3092675200 6031481761

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The smallest Carmichael Number with fifteen prime factors: 6553130926752006031481761 = 11 x 13 x 17 x 19 x 29 x 31 x 41 x 43 x 61 x 71 x 73 x 109 x 113 x 127 x 181. Note that the sum of prime factors is a palindromic semiprime which is the product of two palindromic primes: 11+13+17+19+29+31+41+43+61+71+73+109+113+127+181 = 939 = 3 x 313. [Carmichael]