Do you consider the LSI-11 a microcomputer? It's an implementation of a PDP-11 using an 8-bit microprocessor under the hood.
11Logo was ported to the LSI-11, which was the processor for the commercialized Logo computer (the 3500) from General Turtle. This happened around 1978, which is clearly before the earliest "true micro" Logo ~1980.
Ten billion can be represented in 34 bits, never mind 64. The hexadecimal representation (in which each digit contains four bits) is 0x2540BE400.
The maximum (unsigned) 64-bit integer is 18446744073709551615. This is (2^64)-1, which is essentially the square of (2^32)-1, which is "about" 4 billion.
In general, you can estimate that every 10 bits ...