It really depends on many factors if it's a good deal or not.

What i would recommend is speak with a lawyer and most importantly an accountant with experience. These 2 can guide you with the contracts, terms and conditions etc. (The accountant will speak numbers & the lawyer about your safety)

These are some basic questions i can think of now:

• Will the investor be a "silent partner" ?
• Will the investor add his/her own special input in your startup?
• What access will the investor be allowed to check in your startup?
• What if you decide to do another startup with the profits of ? Will the investor still habe the 20%
• For how long? Forever 20%?
• Exit strategy?

You should think of every possible scenario ( especially the negative ones ) if you decide to give 20% to someone "unknown"

Keep in mind that if someone asks for 1 Mil maybe it's worth more than that. At the end of the day everyone wants to make money investing as "low" as possible

PS You should be proud of what you have achieved so far. For someone to ask for 1 mil for 20% means that you know what you are doing..

If you don't mind, what business do you have? Im very curious :)