Question

I have an integer variable, that can get a value larger than 4294967295.
What type should I use for it?

Answer 1

You can use long (Int64):

The Int64 value type represents integers with values ranging from negative 9,223,372,036,854,775,808 through positive 9,223,372,036,854,775,807.

An alternative is ulong (UInt64):

The UInt64 value type represents unsigned integers with values ranging from 0 to 18,446,744,073,709,551,615.

If that’s not enough look at BigInteger:

Represents an arbitrarily large signed integer.