E

Base of the natural logarithms, approximately 2.71828.

const val E: Double = 2.718281828459045(source)
import kotlin.math.E
import kotlin.math.exp

fun main() {
    val exponent = 3.0

    println("E = $E")
    println("E raised to $exponent: ${exp(exponent)}")
    println("E * $exponent = ${E * exponent}")
}

Source