[ January 16, 2014 ]
Gathering prime factors of nine- and pandigitals
and extracting statistical information from the data

What is the largest prime factor in each case ?

[Answered]

What prime factor(s) has the least frequency of appearing ?

[Answered]

How many palindromic prime factors are there in both cases ?

[Answered]

List of smallest and largest nine-/pandigital 3^k * semiprimes ?

[Answered]

To start with I give the smallest and largest nine- and pandigital prime factorization. 123456789 = 32 x 3607 x 3803 987654321 = 32 x 172 x 379721 yielding already this subset {... ,3,...,17,...,3607,...,3803,...,379721,... } and 1023456789 = 34 x 2221 x 5689 9876543210 = 2 x 32 x 5 x 172 x 379721 yielding already this subset {2,3,5,...,17,...,2221,...,5689,...,379721,... }