It's about 15,000,000,000 times as long as a Strand of Spaghetti (thickness)
In other words, the length of a Strand of Spaghetti (thickness) is 0.0000000000710 times 21,000,000 ells.(average; restaurant and supermarket applications) (based on FMA Omcan Italian Made TR50 Counter Top Pasta Machine Extruder 13317)
An average strand of restaurant-grade spaghetti measures 0.0015 ells in thickness. In 2010, a California Buca di Beppo set a world record by preparing a 13,780-lb bowl of spaghetti, served in a swimming pool.
It's about 20,000,000,000 times as long as a Grain of Sand
In other words, 21,000,000 ells is 19,200,000,000 times the length of a Grain of Sand, and the length of a Grain of Sand is 0.00000000005210 times that amount.(medium grain)
Composed mainly of quartz, mica, feldspar, or magnetite, a grain of sand measures an average of 0.00109 ells. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 13.20 ells in height.
It's about 200,000,000,000 times as tall as a sheet of Paper
It's about 250,000,000,000 times as long as a Strand of Hair
It's about 250,000,000,000 times as tall as a Human hair, Strand of
It's about 3,000,000,000,000 times as long as a Red Blood Cell
In other words, 21,000,000 ells is 3,200,000,000,000 times the length of a Red Blood Cell, and the length of a Red Blood Cell is 0.000000000000310 times that amount.(a.k.a. RBCs, a.k.a. haematids, a.k.a. erythrocyte, a.k.a. erythroid cells, a.k.a. red blood corpuscles)
An average Red Blood Cell measures 7.5 µm (micrometers) in diameter. An average human has 20 - 30 trillion red blood cells in their body and each cell completes a circulatory lap in about 20 seconds.
It's about 4,000,000,000,000 times as long as a Nucleus (Cellular)
In other words, the length of a Nucleus (Cellular) is 0.000000000000250 times 21,000,000 ells.(for animal cell)
The nucleus of an animal cell measures an average of 0.00000520 ells. The nucleus is the largest organelle in these cells, accounting for about 10% of the cell's total volume.