if (x > 0.0 && isFinite(x)) {
      long significand = getSignificand(x);
      return (significand & (significand - 1)) == 0;
    }
    return false;
  }

  /**
   * Returns the base 2 logarithm of a double value.
   *
   * <p>Special cases:
   *
   * <ul>
   *   <li>If {@code x} is NaN or less than zero, the result is NaN.
   *   <li>If {@code x} is positive infinity, the result is positive infinity.