Gigasecond in Kotlin

// Calculate the moment when someone has lived for 10^9 seconds.
import java.time.LocalDate
import java.time.LocalDateTime
import java.time.Month

fun main(args: Array<String>) {
    // Should print 2043-01-01T01:46:40
    println(Gigasecond(LocalDate.of(2011, Month.APRIL, 25)).date)
    
    // Should print 2009-02-19T01:46:40
    println(Gigasecond(LocalDate.of(1977, Month.JUNE, 13)).date)
}

data class Gigasecond(val dobWithTime: LocalDateTime) {
    constructor(dateOfBirth: LocalDate) : this(dateOfBirth.atStartOfDay())

    private val GIGASECOND = Math.pow(10.0, 9.0).toLong()
    val date: LocalDateTime = dobWithTime.plusSeconds(GIGASECOND)
}