There are 33 consonants in Saṃskṛtam. They are called व्यञ्चनानि.
A pure consonant is linguistically defined to be one without any vowel attached to it. But constants are meaningful only when uttered with vowel.
Consonants consist of: Five class consonants each consisting of five consonants / वर्गव्यञ्चनानि [25]

Semi-vowels / अन्तस्थाः [4].

Sibilant / ऊष्माणः [3]. They are hard - Aspirate.

Soft-Aspirate / ह [1]. This also comes under Sibilants.