This number is a composite.
A composite string S formed from the digits 1, 3, 7 and 9. There are 74 primes embedded in S, read left-to-right only. This is the maximal quantity known for 20 digits. Found by Dmitry Kamenetsky. [Rivera]
Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell