महाभारतः mahābhārataḥ - book-1, chapter-2, verse-19

अक्षौहिण्याः प्रसंख्यानं रथानां द्विजसत्तमाः ।
संख्यागणिततत्त्वज्ञैः सहस्राण्येकविंशतिः ॥१९॥

19. akṣauhiṇyāḥ prasaṁkhyānaṁ rathānāṁ dvijasattamāḥ ,
saṁkhyāgaṇitatattvajñaiḥ sahasrāṇyekaviṁśatiḥ.

19. akṣauhiṇyāḥ prasaṁkhyānam rathānām dvijasattamāḥ
saṁkhyāgaṇitatattvajñaiḥ sahasrāṇi ekaviṁśatiḥ

19. O best among the twice-born, those who are skilled in the principles of numeration and calculation declare that the count of chariots in an Akṣauhiṇī is twenty-one thousand.

Words meanings summery:

• अक्षौहिण्याः (akṣauhiṇyāḥ) - pertaining to the large army division whose components are being enumerated (of an akṣauhiṇī)

• प्रसंख्यानम् (prasaṁkhyānam) - the total count or number of military units within an akṣauhiṇī (enumeration, calculation, count)

• रथानाम् (rathānām) - specifies that the count refers to chariots (of chariots)

• द्विजसत्तमाः (dvijasattamāḥ) - an address to the audience, implying they are Brahmins or learned individuals (O best among the twice-born)

• संख्यागणिततत्त्वज्ञैः (saṁkhyāgaṇitatattvajñaiḥ) - refers to the experts providing the numerical information (by those who know the principles of calculation and numeration)

• सहस्राणि (sahasrāṇi) - part of the numerical count for chariots (thousands)

• एकविंशतिः (ekaviṁśatiḥ) - specifies the number of thousands (21,000) (twenty-one)

Words meanings and morphology

अक्षौहिण्याः (akṣauhiṇyāḥ) - pertaining to the large army division whose components are being enumerated (of an akṣauhiṇī)

(noun)

Genitive, feminine, singular of akṣauhiṇī

akṣauhiṇī - an akṣauhiṇī (a specific very large army division)

प्रसंख्यानम् (prasaṁkhyānam) - the total count or number of military units within an akṣauhiṇī (enumeration, calculation, count)

(noun)

Nominative, neuter, singular of prasaṁkhyāna

prasaṁkhyāna - computation, enumeration, calculation, detailed numbering

action noun

derived from pra-sam-√khyā + ana

Prefixes: pra+sam

Root: khyā

रथानाम् (rathānām) - specifies that the count refers to chariots (of chariots)

(noun)

Genitive, masculine, plural of ratha

ratha - chariot, car, vehicle

द्विजसत्तमाः (dvijasattamāḥ) - an address to the audience, implying they are Brahmins or learned individuals (O best among the twice-born)

(noun)

Vocative, masculine, plural of dvijasattama

dvijasattama - best among the twice-born (Brahmins, Kshatriyas, Vaishyas)

Compound type : tatpurusha (dvija+sattama)

• dvija – twice-born (a Brahmin, Kshatriya, or Vaishya), a bird, a tooth
  noun (masculine)
• sattama – best, most excellent, most virtuous
  adjective
  superlative of sat (good, existent)

संख्यागणिततत्त्वज्ञैः (saṁkhyāgaṇitatattvajñaiḥ) - refers to the experts providing the numerical information (by those who know the principles of calculation and numeration)

(noun)

Instrumental, masculine, plural of saṁkhyāgaṇitatattvajña

saṁkhyāgaṇitatattvajña - one who knows the principles of numeration and calculation, an expert in arithmetic

Compound type : tatpurusha (saṁkhyā+gaṇita+tattva+jña)

• saṁkhyā – number, numeration, calculation
  noun (feminine)
  action noun
  Prefix: sam
  Root: khyā
• gaṇita – counting, arithmetic, calculation
  noun (neuter)
  past participle
  from √gaṇ
  Root: gaṇ (class 10)
• tattva – truth, reality, principle, essence
  noun (neuter)
• jña – knowing, acquainted with, wise, a knower
  adjective
  agent noun
  derived from √jñā
  Root: jñā (class 9)

सहस्राणि (sahasrāṇi) - part of the numerical count for chariots (thousands)

(noun)

Nominative, neuter, plural of sahasra

sahasra - thousand

एकविंशतिः (ekaviṁśatiḥ) - specifies the number of thousands (21,000) (twenty-one)

(numeral)