This number is a prime.
216401 is the first instance of a sequence of five primes ending with the digit 1, i.e., 216401, 216421, 216431, 216451, 216481. [Ashiru]
216401 is the first instance of a sequence of five primes ending with the digit 1, i.e., 216401, 216421, 216431, 216451, 216481. [Ashiru]