4 is the smallest squared prime (p 2) and the only even number in this form. 4 is also the only square one more than a prime number. A number is a multiple of 4 if its last two digits are a multiple of 4. For example, 1092 is a multiple of 4 because 92 = 4 × 23. In addition, 2 + 2 = 2 × 2 = 2 2 = 4.

