what are all the prefixes?

Answer 1

“If you were to examine the 20,000 most used English words, you would find that about 5,000 of them contain prefixes and that 82 percent (about 4,100) of those words use one of only fourteen different prefixes out of all the available prefixes in the language.”

ab- (away from)
be- (on all sides, overly)
de- (reversal, undoing, downward)
dis-, dif- (not, reversal)
ex- (out of, former)
pre- (before)
re- (again, restore)
un- (do the opposite of)
ad- (to, toward)
com-, con-, co- (with, together)
en-, em- (in, into, to cover or contain)
in- (into, not)
pro- (in favor of, before)
sub- (under, beneath)

Interestingly enough, none of the technical prefixes from the metric system are here such as:
kilo
mega
giga
tera
milli
micro
nano
pico
femto
atto

Answer 2

If you google "Latin prefixes" and/or "Greek prefixes" it will give you the complete list. Voila!

Answer 3

i dont think this is all, but some are:
re
dis
un
pre
de
in
non
ab
be
ex
ad
com
en
pro
sub