There are a handful of 2,000,000-watt stations in the Middle East and I
believe at least one in Europe. I know of nothing more powerful.

My outdated edition of the World Radio/TV Handbook lists Longwave
stations in Sweden (171 kHz) and Russia (261 kHz) that claimed to be
2,500,000 watts, as well as a number of 2,000,000-watt Longwave
stations in the Middle East, Asia, and Europe.

Also, near St. Petersburg, Russia, there's a station on 1494 kHz that
transmits 1,200,000 watts (with a transmitter capable of 2 MW) through
a *26-tower* directional array with a gain of 25 dB, aimed at
Scandinavia. The array is more than 1-1/2 miles from end to end.

BTW, right in my town, there's a 5,000,000-watt UHF TV station, but
that's the ERP due to antenna gain, not actual transmitter power.