How to format a number using "toFixed" only if it is not integer in Javascript?

Question

I have a function that returns me a number, which can be integer, like: 440; or it can be broken, like 466.1638231521. But I need to have a way to, from the function, find out if the number is broken. If it is whole, I will leave it the way it is, otherwise I will format using toFixed(4).

function geraFrequenciaNota(semitons) {
  let divisor = (semitons / 12)
  let exponenciado = Math.pow(2, divisor)
  let multFreq = 440 * exponenciado
  return multFreq.toFixed(4)
}

That’s my code so far, the problem is that when the number is Integer, for example 440, I want it to return 440, not 440.0000.