Why is BASE_REWARD_FACTOR equal to 64?

Question

This number '64' keeps coming up throughout Ethereum. There are 64 committees and 64 shards.

Is any of this related to the base reward factor being equal to 64? Why is the base reward factor 64?

Answer 1

From Ben Edgington on his Ethereum 2.0 Annotated Specification:

This is the big knob to turn to change the issuance rate of Eth2. Almost all validator rewards are calculated in terms of a "base reward" which is calculated as, effective_balance * BASE_REWARD_FACTOR // integer_squareroot(total_balance) // BASE_REWARDS_PER_EPOCH where effective_balance is the individual validator's current effective balance and total_balance is the sum of the effective balances of all active validators. Thus, the total validator rewards per epoch (the Eth2 issuance rate) could in principle be tuned by increasing or decreasing BASE_REWARD_FACTOR.

I guess it's just a nice number (a power of 2) that gives interesting and desirable results when used for various formulas including reward computation.