Number of galaxies as a function of their host halo mass and H I mass in the ELUCID SAM catalog. The number in logarithmic scale is represented by different colors. We show the result of central (satellite) galaxies in the left (middle) panel. The mean value and standard deviation are shown together with the color map to illustrate the trend more clearly. The average number of satellite galaxies in each halo as a function of mass is shown in the right panel.