Did you know this about prefixes?

Here are examples: compound, impossible, embellish, symbiote.

These are just a different form of con-, in-, en- syn-!

When ever one of those four come before an p, m, or b, the n becomes a m.

Examples:

in + possible = impossible (because the suffix is before a p)

con + pound = compound (because the suffix is before a p)

There's some other rules for some of these before other letters, here are just two examples:

con becomes col before l (collaborate)

con become cor before r (correlate)

So yeah, I guess English has some written sandhi (even if it's all from latin/greek)! I also don't know if this rule is still productive in the language, but then again theres not many new words starting with con, in, en, and syn so those themselves are not very productive. And theres an even smaller chance for one of those words to precede m, p or b.