guava/src/com/google/common/math/DoubleMath.java
@GwtIncompatible // com.google.common.math.DoubleUtils
  public static boolean isPowerOfTwo(double x) {
    if (x > 0.0 && isFinite(x)) {
      long significand = getSignificand(x);
      return (significand & (significand - 1)) == 0;
    }
    return false;
  }
@GwtIncompatible // com.google.common.math.DoubleUtils
  public static boolean isPowerOfTwo(double x) {
    if (x > 0.0 && isFinite(x)) {
      long significand = getSignificand(x);
      return (significand & (significand - 1)) == 0;
    }
    return false;
  }
Returns {@code true} if {@code x} is exactly equal to {@code 2^k} for some finite integer
{@code k}.