Neptune has a mass of 1.0243×1026 kilograms, or about
17.147 times that of Earth. Wikipedia has additional information,
and a link is provided below to their post on this, the new "last
planet" now that Pluto has been "demoted" to a planetary body.
Neptune's density is 1.638 g/cm³. That means that in every cm cubed
it weighs 1.638 grams.