It's about 250,000,000 times as long as an Aspirin
In other words, 623 leagues is 250,000,000 times the length of an Aspirin, and the length of an Aspirin is 0.0000000040 times that amount.(for up & up aspirin, 325mg, regular strength tablets) (a.k.a. acetylsalicylic acid, a.k.a. ASA)
A single aspirin tablet measures 0.00000250 leagues in diameter. One of the most common medicines in the world and a foundation of worldwide health systems, an estimated 40,000 metric tons of aspirin are consumed each year.
It's about 2,000,000,000 times as wide as a Strand of Spaghetti
In other words, 623 leagues is 2,000,000,000 times the width of a Strand of Spaghetti, and the width of a Strand of Spaghetti is 0.00000000050 times that amount.(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 0.000000310 leagues 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 3,000,000,000 times as long as a Grain of Sand
In other words, 623 leagues is 2,770,000,000 times the length of a Grain of Sand, and the length of a Grain of Sand is 0.000000000361 times that amount.(medium grain)
Composed mainly of quartz, mica, feldspar, or magnetite, a grain of sand measures an average of 0.0000002250 leagues. In 2007, a team of seven in Myrtle Beach created the world's tallest sandcastle, which measured 0.00272 leagues in height.
It's about 30,000,000,000 times as tall as a sheet of Paper
In other words, 623 leagues is 30,000,000,000 times the height of a sheet of Paper, and the height of a sheet of Paper is 0.000000000030 times that amount.(for US Letter, a.k.a. ANSI A; 215.9mm by 279.4mm (8.5 in x 11 in); 20lb)
A single sheet of 20 lb, 8.5 inch x 11 inch paper is just 0.0000000200 leagues thick. This style of paper weighs a mere 5 g per sheet.
It's about 35,000,000,000 times as wide as a Strand of Hair
In other words, 623 leagues is 35,000,000,000 times the width of a Strand of Hair, and the width of a Strand of Hair is 0.000000000029 times that amount.(average)
A strand of human hair averages 99 µm (micrometers), with blond hair being the finest and black hair the thickest. On a healthy scalp, each strand of hair will last up to 6 years.
It's about 450,000,000,000 times as long as a Red Blood Cell
In other words, 623 leagues is 460,000,000,000 times the length of a Red Blood Cell, and the length of a Red Blood Cell is 0.0000000000022 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 600,000,000,000 times as long as a Cell's Nucleus
In other words, 623 leagues is 580,000,000,000 times the length of a Cell's Nucleus, and the length of a Cell's Nucleus is 0.0000000000017 times that amount.(for animal cell)
The nucleus of an animal cell measures an average of 0.00000000110 leagues. The nucleus is the largest organelle in these cells, accounting for about 10% of the cell's total volume.