This number is a composite.
The largest number with distinct digits such that all its substrings of length 1-2 are primes (5, 3, 7, 53 and 37 are all primes). [Gudipati]
The largest number with distinct digits such that all its
substrings of length 1-2 are primes (5, 3, 7, 53 and 37 are
all primes). [Gudipati]