Question and the examples
Examples: $n=16$, then we can swap $6$ and $1$ to get a prime $61$
$n=92$ , we can swap the digits to get the prime 29
What is the sufficient criteria for there to exist a rearrangement of a number's digit such that number becomes a prime? It may be quickly noted that numbers with all digits even are immediately disqualified.
A way to find total number of primes from permutation of a number $n$'s digits
Note: After googling, I found this method was just Sieve of Eratosthenes
If I have a number of length $n$, then I found an algorithm to find number of prime permutation of it's digits. I remove the permutations which are divisible by any number $k<n$ till I reach $n$.
For example if I have 12345, I have the set of numbers $\{1,2,3,4 ,5 \}$ for a total of 5! permutations, from which first I remove the numbers divisible by two, then three , then four, finally I add back the numbers divisible by two and four.
Related topics
There are the permutable primes, which are primes which stay prime independent of shuffling of digits. It is clear that this is a subset of the kind of numbers which satisfy the criteria in the question.