52

Math

is the integer between.

Math features

 * is an even number.
 * 52, being equal to 13 &times; 4, is the number of cards in a deck.
 * 52 is the only two-digit number where its palindrome multiplied by 2 added to 2 is equal to that number.

&frac12;

 * $1⁄2$ is half of