# minimal prime

Every prime number, when written in base ten, has one of the following primes as a substring:

2, 3, 5, 7, 11, 19, 41, 61, 89, 409, 449, 499, 881, 991, 6469, 6949, 9001, 9049, 9649, 9949, 60649, 666649, 946669, 60000049, 66000049, 66600049

These are the minimal primes. A string *a* is a substring of another
string *b*, if *a* can be obtained from *b* by deleting
zero or more of the characters in *b*. For example, 392 is a substring
of 639802.