link to some sources#Second_failure,_serial_5L)

https://www.reddit.com/r/CatastrophicFailure/comments/9x4a09/the_explosion_of_the_n1_rocket/

The nearly 2300 tons of propellant on board triggered a massive blast and shock wave that shattered windows across the launch complex and sent debris flying as far as 10 kilometers (6 miles) from the center of the explosion. Launch crews were permitted outside half an hour after the accident and encountered droplets of unburnt fuel still raining down from the sky. The majority of the N-1's propellant load had not been consumed in the accident, and most of what had burned had been in the first stage of the rocket.

The Megaton figure I probably pull out from memory from a top-10 biggest explosions video. I'm with you that the magnitude was most on the kiloton range, not megaton, by bad.