public class Benchmarks
{
    private BigInteger _smallPowerOfTwo;
    private BigInteger _smallNotPowerOfTwo;
    private BigInteger _largePowerOfTwo;
    private BigInteger _largeNotPowerOfTwo;

    [GlobalSetup]
    public void GlobalSetup()
    {
        _smallPowerOfTwo    = BigInteger.Parse("0000000000000001000000000000000000000000000000000000000000000000", NumberStyles.BinaryNumber);
        _smallNotPowerOfTwo = BigInteger.Parse("0000000000000001000000000000000001110011011011000010100011101111", NumberStyles.BinaryNumber);

        Random rnd = new Random(123456);
        
        var bytes = new byte[1 + 256];
        bytes[0] = 1;
        
        _largePowerOfTwo = new BigInteger(bytes, isBigEndian: true);
        
        rnd.NextBytes(bytes.AsSpan(1));

        _largeNotPowerOfTwo = new BigInteger(bytes, isBigEndian: true);
    }

    [Benchmark]
    public bool SmallPowerOfTwo() => _smallPowerOfTwo.IsPowerOfTwo;
    
    [Benchmark]
    public bool SmallNotPowerOfTwo() => _smallNotPowerOfTwo.IsPowerOfTwo;
    
    [Benchmark]
    public bool LargePowerOfTwo() => _largePowerOfTwo.IsPowerOfTwo;
    
    [Benchmark]
    public bool LargeNotPowerOfTwo() => _largeNotPowerOfTwo.IsPowerOfTwo;
}