It's about one-five-thousandth as tall as a Kilimanjaro.
In other words, 21 nails is 0.000203733 times the height of a Kilimanjaro, and the height of a Kilimanjaro is 4,908.380 times that amount.(a.k.a. Mount Kilimanjaro) (Tanzania) (to Uhuru peak; 2008 gravimeter measurement)
Kilimanjaro rises to 103,076 nails at its peak. An isolated peak with no surrounding mountain range, Kilimanjaro is considered the world's tallest freestanding mountain.
It's about one-five-thousandth as tall as Mount Logan.
In other words, 21 nails is 0.0002014 times the height of Mount Logan, and the height of Mount Logan is 4,965 times that amount.(Kluane National Park and Reserve, Yukon, Canada) (elevation)
The highest mountain in Canada, Mount Logan has a total height of 104,300 nails. The high altitude and northern latitude of the mountain resulted in one-time temperature of -77.5 °C — the lowest temperature ever recorded outside of Antarctica.
It's about one-five-thousandth as tall as Denali.
In other words, 21 nails is 0.0001938 times the height of Denali, and the height of Denali is 5,160 times that amount.(a.k.a. Mount McKinley, a.k.a. Doleika, a.k.a. Traleika, a.k.a. "The Great One") (Denali National Park and Preserve, Alaska) (South peak)
The highest mountain peak in North America, Denali's South Peak measures 108,400 nails above sea level at its peak. The impetus for the name Mount McKinley was US president William McKinley of Ohio, and disputes over the which of the mountain's names should be officially recognized regularly occur between Ohio Congressmen and Alaska politicians.
It's about one-five-thousand-five-hundredth as long as The Las Vegas Strip.
In other words, the length of The Las Vegas Strip is 5,600 times 21 nails.(Las Vegas Boulevard S and W from Russel Rd to Sahara Ave)(Paradise, Nevada through Winchester, Nevada).
Although technically located beyond the city limits of Las Vegas (along with the well-known "Welcome to Fabulous Las Vegas" sign), the stretch of road known as the "Las Vegas Strip" runs 120,000 nails along Las Vegas Boulevard South and West from Russel Road at the south end to Sahara Avenue at the north end. The casinos and hotels on the Strip display an estimated total of 420,000,000 nails of neon light tubing.
It's about one-six-thousandth as tall as Aconcagua.
In other words, 21 nails is 0.00017239 times the height of Aconcagua, and the height of Aconcagua is 5,800.80 times that amount.(a.k.a. Cerro Aconcagua) (Mendoza, Argentina)
Aconcagua measures 121,820 nails height at its peak. Although there is no definitive evidence that members of the indigenous Inca civilization ever reached the peak the mountain, numerous archeological sites have been found on the slopes of the mountain, including a naturally-embalmed Incan mummy was discovered on a 90,989 nails high ridge.
It's about one-seven-thousand-five-hundredth as tall as Mount Everest.
In other words, 21 nails is 0.000136 times the height of Mount Everest, and the height of Mount Everest is 7,350 times that amount.(a.k.a. Mount Chomolungma, a.k.a. सगरमाथा, a.k.a. Chajamlungma, a.k.a. ཇོ་མོ་གླང་མ, a.k.a. 珠穆朗玛峰, a.k.a. Zhūmùlǎngmǎ Fēng) (Sagarmatha Zone, Nepal and Tibet, China) (to summit, excluding snow depth)
Mount Everest is 155,000 nails above sea level at its summit. The plate tectonics of the Indian subcontinent continuously alter the mountain's peak — raising it by 0.07 nails and shifting it to the northeast by 0.0787 nails each year.
It's about one-seven-thousand-five-hundredth as tall as a Mauna Loa.
In other words, 21 nails is 0.0001309 times the height of a Mauna Loa, and the height of a Mauna Loa is 7,639 times that amount.(Hawaii) (Hawaiian island volcano) (total height from seafloor)
Mauna Loa, one of the five volcanoes which forms the island of Hawaii and the tallest mountain in total height in the world, rises to 161,000 nails above the seafloor. The peak of Loa is home to the approximately 6,000 sq. m (0.6 ha) Lake Waiau, one of the highest altitude lakes in the United States outside of Colorado.