1221
1221 Amor gave its name to a whole orbital class.
- Odd
- Composite
Where 1221 fits
Why 1221 is special
Asteroids that approach Earth's orbit without crossing it are called Amors after this one, which is how an individual object becomes a category.
1221 is part of
Factors & digit properties
- Divisors (8)
- 1, 3, 11, 33, 37, 111, 407, 1221
- Prime factorisation
- 3 × 11 × 37
- Digit sum
- 6
- Digital root
- 6
Representations
- Decimal
- 1221
- Binary
- 10011000101
- Octal
- 2305
- Hexadecimal
- 4c5
- Roman numeral
- MCCXXI
- Scientific notation
- 1.221 × 10^3
Other mathematical patterns
- Palindromic number
- Deficient number
- Happy number
Related numbers & connections
Resonance with Jupiter steadily raises eccentricity, which is one way objects arrive on Earth-crossing orbits.
View 887 →Science
1221 Amor is the namesake of the Amor group, near-Earth asteroids with perihelia outside Earth's orbit but within 1.3 astronomical units of the Sun.
DocumentedSciencePeriod: 1932–
Common questions
Is 1221 a prime number?
No, 1221 is not prime.
What are the factors of 1221?
The factors of 1221 are 1, 3, 11, 33, 37, 111, 407, 1221.
What is 1221 in Roman numerals?
1221 in Roman numerals is MCCXXI.
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