Purely by length (ignoring checksum, RNG, etc.), it's 2048600 / 204824 or 2048576 times more secure than 24 words.
The only thing it is more secure against is someone blindly trying to guess your seed phrase, which pretty much no one is ever going to do. It does not make your wallet, your private keys, or your coins any more secure.
I agree, i simply show the number.
You can't generate 600 words seed with iancoleman tool, but even if it's possible there's security concern generate random number with browser.
You can. Click on "Show entropy details", and then make sure the drop down box shows "Use Raw Entropy (3 words per 32 bits)". You can then enter as much entropy as you like and it will generate as long a seed phrase as you like. You will obviously need to generate your own entropy to do this.
I know, but almost no one use the feature or use entropy from secure source (such as
/dev/urandom).