efficient prime test c++

inline bool Root::is_prime( unsigned int number )
{
    if ( ( (!(number & 1)) && number != 2 ) || (number < 2) || (number % 3 == 0 && number != 3) )
        return (false);

    for( int k = 1; 36*k*k-12*k < number; ++k)
        if ( (number % (6*k+1) == 0) || (number % (6*k-1) == 0) )
            return (false);
    return true;
}