13. "My phone number," said the trip leader to the kids, "is a five-digit number. The first digit represents a prime number, and the last two digits are obtained from the previous pair, which represents a prime number, by rearrangement and form a perfect square. The number, reversed to this phone number, is even." What is the trip leader's phone number?
13. Since the reversed number is even, the first digit of the number is 2. (This is the only even prime number.) Of the exact squares 16, 25, 36, 49, 64, 81, only the number 16 gives a reversed prime number 61. Therefore, the phone number of the leader is $2-61-16$.