is.integer(66) # FALSE

is.wholenumber <- function(x, tol = .Machine$double.eps^0.5)  abs(x - round(x)) < tol
is.wholenumber(1) # is TRUE

check.integer <- function(x) {
    x == round(x)
}

x%%1==0,

min(abs(c(x%%1, x%%1-1))) < tol,

all.equal(a, as.integer(a))

testInteger <- function(x){
  test <- all.equal(x, as.integer(x), check.attributes = FALSE)
  if(test == TRUE){ return(TRUE) }
  else { return(FALSE) }
}

check.integer <- function(N){
    !grepl("[^[:digit:]]", format(N,  digits = 20, scientific = FALSE))
}

check.integer(3243)
#TRUE
check.integer(3243.34)
#FALSE
check.integer("sdfds")
#FALSE

> check.integer(222e3)
[1] TRUE

> 2/49*49
[1] 2
> check.integer(2/49*49)
[1] FALSE
> is.wholenumber(2/49*49)
[1] TRUE

> is.integer(66L)
[1] TRUE

> is.wholenumber(1+2^-50)
[1] TRUE
> check.integer(1+2^-50)
[1] FALSE

all(floor(x) == x, na.rm = TRUE)

testInteger <- function(x){
test <- all.equal(x, as.integer(x), check.attributes = FALSE)
}

print(testInteger(2/49*49))
[1] "Mean relative difference: 0.5"

as.integer(2/49*49)
[1] 1