Kotlin also offers adding properties to existing types with extension properties. Just as extension functions have the type they are extending before a function name, extension properties are like normal properties with the addition of the extended type before the property name. The function we wrote in the previous section can also be written as a property:

val Int.isPowerOf2: Boolean

    get() = this > 0 && ((this and this - 1) == 0)

Now, we can access this property on any variable of Int type:

val n = 16

val isPowerOf2 = n.isPowerOf2

You can also have a mutable extension property, where you'd have to implement the set method also.