4294967291

This number is a prime.

The largest prime below 2^32 that also switches to composite after deleting any of its digits, one at a time. This is an example of a "weakly prime to digits deletion." The following ten integers are composite: 294967291, 494967291, 424967291, 429967291, 429467291, 429497291, 429496291, 429496791, 429496721, 429496729 [Rivera]