A capicúa figure or palindrome number is a number that is read the same from left to right as from right to left. For example, the numbers 22, 111111, 343, 5665, and 17371 are capicua. The term comes from the Catalan expression cap i cua (which means 'head and tail'). Many people are attracted to these numbers and collect them on the most diverse objects: show tickets, metro tickets, car license plates, lottery tickets …
Obviously there are prime capiquuas, which can only divide by themselves. The first is 11, followed by 101 and 313. But the funny thing is that to find the fourth you have to go to a 39-digit number !: 1919180808180919090909190818080819191 .
