622
622 is year one of the Islamic calendar, marking the Hijra.
- Even
- Composite
Where 622 fits
Why 622 is special
The migration from Mecca to Medina, not Muhammad's birth or the first revelation, is the point from which Islamic years are counted. Because the calendar is purely lunar its year is about eleven days shorter than the solar one, so the two do not stay in step.
622 is part of
Factors & digit properties
- Divisors (4)
- 1, 2, 311, 622
- Prime factorisation
- 2 × 311
- Digit sum
- 10
- Digital root
- 1
Representations
- Decimal
- 622
- Binary
- 1001101110
- Octal
- 1156
- Hexadecimal
- 26e
- Roman numeral
- DCXXII
- Scientific notation
- 6.220 × 10^2
Other mathematical patterns
- Deficient number
- Happy number
- Semiprime
Related numbers & connections
Two starting points for different periodisations — the deposition of the last western Roman emperor, and the migration from which Islamic years are counted. Neither was experienced as an epoch by the people present.
View 476 →Other connections
- contrasts with476
why?
Strength 0.50, confidence "high".
Religion & belief
The Islamic calendar counts from the migration to Medina in 622, not from Muhammad's birth or first revelation. It is strictly lunar, so its year runs about eleven days short of the solar one and Islamic dates move steadily against the Gregorian calendar rather than staying fixed.
DocumentedReligion & beliefPeriod: 622
Common questions
Is 622 a prime number?
No, 622 is not prime.
What are the factors of 622?
The factors of 622 are 1, 2, 311, 622.
What is 622 in Roman numerals?
622 in Roman numerals is DCXXII.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 3 August 2026