冪乗演算子 a ^^ b (aのb乗)
let a = BigInt("7")
let b = BigInt("2")
print(a ^^ b)//→49
平方根関数 sqrt(of: n ) (nの平方根)
let a = sqrt(of:BigInt("60"))
print(a)//→7
平方数判定関数 isPerfectSquare(n) (nは平方数か)
let a = BigInt("121")
print( isPerfectSquare(a) )→true
素数判定関数 isProbablePrime( n ) (n は素数か)
let a = BigInt("121")
let b = isProbablePrime(a)
print(b)//→false
