4649
This number is a prime.
The smallest composite-digit prime whose prime factors of its digits form another prime when they are concatenated left-to-right. [Honaker]
The greatest prime factor of any seven-digit repdigit. [La Haye]
4649 is formed from two consecutive semiprimes (46 and
49); each of them formed from semiprime digits. [Silva]
The smallest prime whose each digit as well as number of
digits are all composite numbers. [Gudipati]
(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