A planet is estimated to have a mass of 1.8344 x 1024 kg. Assuming the planet is a sphere of average radius 5399 km, calculate the average density of the planet in units of g/cm3.

density=mass/volume

so i convert the 1.8344 x 10^24 kg to g= c

Volume of sphere=4/3 x pie x r^3

=4/3 x pie x 5399^3

= 6.59217 x 10^11 km^3

km^3 --> 6.59217 x 10^26 cm^3

then d= 1.8344 x 10^24 g/6.59217 x 10^26 cm^3

=0.002783

is there anything wrong with my answer?

this is a mutiple choice and the closest answer is

2.78 g/cm3but it just doesnt seem right.

Help is very appreciated, thanks!!