Check the output of
fdisk -l /dev/hda or a similar tool (
sfdisk -l /dev/hda,
parted -l, …).
You can't tell whether a partition is primary or extended from its number. In the classic PC partition scheme, each partition numbered 1, 2, 3 or 4 can be either primary or extended. (It's possible but not recommended to have multiple extended partitions; Linux itself doesn't mind but some management tools do.)
There's an almost-guaranteed way to check without root access: you can look up the size of each partition in
/proc/partitions. The size of extended partitions is always reported as a single block. For instance, in the example below,
sda4 is an extended partition.
major minor #blocks name
8 1 489951 sda1
8 4 1 sda4