9839
This number is a prime.
9839 is a prime p for which the concatenations 1p1, 3p3,
7p7, and 9p9 are all primes (198391, 398393, 798397,
998399). There are only seven primes less than 10000 with
this property: 53, 2477, 4547, 5009, 7499, 8831, and 9839. [Keith]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell