def number_of_radial_points(Z):
    """
    select the number of radial grid points for the subintegral
    around an atom with atomic number Z
    """
    # Hydrogen atom receives an initial quota of 20 points
    Nr = 20
    # Each shell receives an additional 5 points
    if Z >= 2:
        Nr += 5
    if Z >= 11:
        Nr += 5
    if Z >= 19:
        Nr += 5
    if Z >= 37:
        Nr += 5
    if Z >= 55:
        Nr += 5
    if Z >= 87:
        Nr += 5
        
    return Nr