You most likely will need to do things in C++ as blueprint is very limited in type precision variants. In C++ there type TBigInt allowing to work with higher then standard 32-bit or 64-bit integers
Note that this is a emulation hack as both compiler and CPUs don’t support operation on bigger numbers.I don’t think you will be able to input values in to it and do operations with higher number then then 64-bit (or else you will use other TBigInt), but there should be no problem by adding smaller numbers and just displaying result with ToString()
You can also just use int64 or uint64 (if you don’t need negative numbers), if 64-bit numbers are enough for you, as standard integer blueprints is int32 so they are bigger. Maximum 64-bit unsigned max number is 18446744073709551615. Note that those types are nativly supported only by 64-bit CPUs, if you build for 32-bit compiler will do some emulation work similarly to TBigInt (if i’m not mistaken).