as.numeric(date)

data = as.POSIXct("1/1/2021  1:05:00 AM",
                  format="%m/%d/%Y  %H:%M:%S %p")
  
# display
print(data)
  
# convert to numeric
print(as.numeric(data))

[1] "2021-01-01 01:05:00 UTC"
[1] 1609463100

as.numeric(date)/86400

as.numeric(date)/86400/365

data = as.POSIXct("1/1/2021  1:05:00 AM", 
                  format="%m/%d/%Y  %H:%M:%S %p")
  
# display
print(data)
  
# convert to numeric
print(as.numeric(data))
  
# convert to numeric and get days
print(as.numeric(data)/86400)
  
# convert to numeric and get years
print((as.numeric(data)/86400)/365)

[1] "2021-01-01 01:05:00 UTC"
[1] 1609463100
[1] 18628.05
[1] 51.03574

# load the library
library("lubridate")
  
# create date
data = as.POSIXct("1/1/2021  1:05:00 AM", 
                  format="%m/%d/%Y  %H:%M:%S %p")
  
# display
print(data)
  
# get the day
print(day(data))
  
# get the month
print(month(data))
  
# get the year
print(year(data))
  
# get the hour
print(hour(data))
  
# get the minute
print(minute(data))
  
# get the second
print(second(data))

[1] "2021-01-01 01:05:00 UTC"
[1] 1
[1] 1
[1] 2021
[1] 1
[1] 5
[1] 0