It's about 0.000000004 times as long as The Diameter of Earth
In other words, 2.10 inches is 0.0000000041814721 times the length of The Diameter of Earth, and the length of The Diameter of Earth is 239,150,230 times that amount.(Equatorial)
The Earth — not a perfect sphere, but rather an oblate spheroid with bulged middle — has a diameter of approximately 502,215,470 inches at the Equator. The first complete view of Earth's diameter was in a photograph taken from a V-2 rocket launched in 1946 by the United States Army, which reached an altitude of 4,118,400 inches.
It's about 0.000000002 times as long as The Circumfrence of Earth
In other words, 2.10 inches is 0.0000000013310039 times the length of The Circumfrence of Earth, and the length of The Circumfrence of Earth is 751,312,600 times that amount.(Equatorial)
The Earth — not a perfect sphere, but rather an oblate spheroid with bulged middle — has an Equatorial circumference of approximately 1,577,756,500 inches. The first airplane trip around the circumference of the Earth (with a few stops along the way), was completed in 1924 by the United States Army Air Service, and took 175 days.
It's about 0.0000000002 times as long as The Distance from Earth to the Moon
In other words, 2.10 inches is 0.0000000001387485 times the length of The Distance from Earth to the Moon, and the length of The Distance from Earth to the Moon is 7,207,285,000 times that amount.(a.k.a. Luna) (median of semi-major axis, or apigee, and semi-minor axes, or perigee)
The orbit of the Moon around the Earth is elliptical, with an average distance of 15,135,300,000 inches from center-to-center. About 428.376 kg of moon rock have been cataloged on the Earth, from the American Apollo and Soviet Luna Programs, and from samples that have been extracted from meteorites.