Why does R evaluate the following character versus number inequality differently depending on the number?

> Sys.info()
       sysname        release        version 
     "Windows"       "10 x64"  "build 22631" 
      nodename        machine          login 
           "X"       "x86-64"            "X" 
> "158" < 15
[1] FALSE
> "158" < 16
[1] TRUE
> "158"
[1] "158"

I have tried different combinations of characters and numbers, but the above has proven befuddling.