Why does nchar return the wrong values for large numeric variables in R?

Question

From my understanding the input should be converted to character without specifying

"x = ...character vector, or a vector to be coerced to a character vector"

nchar(2015122514204000000)
# 18 
nchar("2015122514204000000")
# 19 

# Replacing the end zeroes with 111111
nchar(2015122514204111111)
# 19

Answer 1

It is doing the following:

as.character(2015122514204000000)
"2.015122514204e+18"

and

nchar("2.015122514204e+18")

is 18.

Try e.g. options(scipen=999) to prevent scientific notation, and nchar(2015122514204000000) will return 19. Hope this helps!