2048 bits are 2048 bits or binary digits. Which means 2048 digits that can be 0 or 1.
In 2048 bits you can put 3.2317...E616 different values. That's the scientific notation of a big number. 1.23E17 would mean 123000000000000000, but 3.2317E616 means actually 3231700607131100730071487668867..., or a number with total 617 decimal digits.
To make it simpler,
- in 1 bit you can store 2 different values (0 or 1).
- In 4 bits you can
store 16 different values (2*2*2*2 or 2^4).
- In 8 bits you can store
256 different values (2*2*2*2*2*2*2*2 or 2^8 or 2E2).
- In 16 bits you
can store 65536 different values (2^16 or 6.5536E4).
- In 32 bits you
can store 4294967296 different values (2^32 or 4.2E9).
- In 64 bits you
can store 2^64 or 1.8E19 different values. That's a number with 20
decimal digits (18446744073709551616).
So in 2048 bits you can store 2^2048 or 3.23E616 different values. That's a number with 617 decimal digits.
I didn't read the first article you cite entirely, but either 1400 is wrong or it's in a different context.
2^10=~1,000
,2^20=~1,000,000
,2^40=~1,000,000,000,000
, etc. So 2^2048 is approx 256 (2^8) with 204 groups of zeros after it.