Minimum and maximum values of "all" cryptocurrencies?
I can't answer for all cryptocurrencies, but for bitcoin, you shoud store values as long and not doubles. The unit of account of bitcoin is the satoshi, a hundred millionth of Bitcoin. Since there can only be 21M BTC ever, that's a maximum of 2.1 quadrillion (2.1 * 10^5) satoshis. That number fits in 64 bits.

For Ethereum, you need 256 bits unsigned integers IIRC.