Well, it turns out I had been given bad advice several months ago, when I was looking into the requirements for taking the MRD (a.k.a.RMD) from my 401K and the IRAs. The amount one has to take depends on the account balances from 12/31 of the previous year, and a percentage from IRS tables. I had been told by my financial advisers that I could add up the accounts, arrive at the total MRD, and then take all of it from any one of the accounts, or a bit from each, or any combination, as long as the total came out to the required minimum --- and back then I found nothing online that disputed that. So I added it all up, and took it all from the 401K.
Surprise. I found a very recent article that says that you cannot combine the 401K with IRAs. You can combine several IRA balances and take money from any of them, but a 401K has to be handled separately. You have to take the 401K's MRD only from the 401K, and you can't take any IRA MRDs from the 401K.
Crap. If I hadn't found that, I'd have been hit with major tax penalty for not having taken any MRD from the IRAs!
So, I did that at 3 am. I took the required amount from each of the IRAs. The IRS will have nothing to complain about.
I'm still a bit confused about why I have to pay a 20% tax "penalty" on the "excess" over the required minimum I took from the 401K. I thought this was my retirement account, and that I'm now old enough to be able to take as much as I want out of there whenever I want --- whatever I need to live on, right? It likely has to do with what portion is "tax free", and anything over that is taxed as income. But I ran the numbers, and if I were to take only the minimum every year, that account wouldn't be drained until I'm 115 years old. I'm not likely to live that long.
BTW, there's no penalty if I take money out of the 401K and roll it over into an IRA, and then I can take all I need from the IRA whenever I need it, taxed as normal income. No penalty. I think. I'll have to look into that next year.