Mathf.NextPowerOfTwo

public static int NextPowerOfTwo (int value);

説明

値以上のもっとも近い 2 のべき乗を返します

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Example() {
        Debug.Log(Mathf.NextPowerOfTwo(7));
        Debug.Log(Mathf.NextPowerOfTwo(139));
    }
}