Sunday Times Teaser 3112 – PIN
by Andrew Skidmore
Published Sunday May 15 2022 (link)
Callum has opened a new current account and has been given a telephone PIN that is composed of non-zero digits (fewer than six). He has written down the five possible rearrangements of his PIN. None of these five numbers are prime; they can all be expressed as the product of a certain number of different primes.
The PIN itself is not prime; it can also be expressed as the product of different primes but the number of primes is different in this case. The sum of the digits of his PIN is a square.
What is the PIN?