All format specifiers that gnuplot has to offer can be found here.
If you don’t like the 2e+07 format you could try setting the format with
set format x "%.0s*10^{%T}"
which gives you a format like 15*10^6.
All format specifiers that gnuplot has to offer can be found here.
If you don’t like the 2e+07 format you could try setting the format with
set format x "%.0s*10^{%T}"
which gives you a format like 15*10^6.