I know that one reason is it is super long and your body can't easily hold it in if it was unraveled.
No, the length increases. When you are alive, the muscles are contracted in folds, and when you die, these folds relax, expanding the small intestine.
permanent folds are called plicae circulares temporary folds are called rugae.
The villi are the tiny finger-like projections that cover the folds of the small intestine. The singular of villi is villus.
circular folds
It's impossible to count. The entire structure of the small intestine is folded and coiled so it's impossible to identify individual folds. Also the small intestine can move around within the abdomen, so changes in shape are normal.
They are called "plicae circulares"
folds and villi
The circular folds or plicae circularis are the permanent folds or ridges of the mucosa.
Peritoneum
It increases the surface area available for absorption of digestion nutrients.
spleen
rugae It's not rugae - for stomach. Small intestine wall is plicae circulares.