What is the maximum channel capacity allowed on the Bitcoin testnet? Using Electrum desktop wallet connected to the testnet, when trying to open a channel  with the amount exceeding 0.16777215 BTC I get the following:

Could not open channel. Exception('Requested channel capacity is over protocol allowed maximum')

Is 0.16777215 BTC hardcoded in Electrum or is it determined by the testnet itself?
I noticed that on the mainnet the maximum capacity is siginificatly higher as some exchanges allow LN withdrawals of 0.5 BTC.
I noticed that on the mainnet the maximum capacity is siginificatly higher as some exchanges allow LN withdrawals of 0.5 BTC

I think they are using wumbo channels:
Is the Lightning Network sufficiently secure and well tested for wumbo channels?