7321
This number is a prime.
The smallest zeroless prime whose product of the first two digits is a concatenation of the 3rd and 4th digits. [Gallardo]
The smallest emirp that splits into an emirp and the corresponding prime subscript (73 is the 21st prime). [Loungrides]
(There is one curio for this number that has not yet been approved by an editor.)
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell