This number is a composite.
289 is the square of the sum of the first four prime numbers, i.e., 289 = (2 + 3 + 5 + 7)2. [Thoms]
(There are 2 curios for this number that have not yet been approved by an editor.)
Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell