1991
Number 1991: Properties, Factors, and Mathematical Facts
Short answer
The number 1991 is an odd composite number with 4 positive divisors. Its prime factorization is 11 × 181. It is also a deficient number and a decimal palindrome, which gives it several notable mathematical relationships.
Is 1991 prime?
ClassificationCompositeParityOddDivisor count4AbundanceDeficient
What is the prime factorization of 1991?
Prime factorization
11 times 181
What are the divisors of 1991?
Divisor count
4
Divisor sum
2,184
Proper divisor sum
193
- 1
- 11
- 181
- 1991
How is 1991 classified?
How is 1991 represented in other numeral systems?
Decimal
1991
Binary
11111000111
Octal
3707
Hexadecimal
7C7
Roman
MCMXCILearn more →
In words
one thousand nine hundred ninety one
Roots and powers
Square root
44.620623 Approximate
Cube root
12.580283 Approximate
Nearest lower square
1936
Nearest higher square
2025
Nearest lower cube
1728
Nearest higher cube
2197
What are the digit properties of 1991?
Which numbers are related to 1991?
Why these results are true
- 1991 is composite because it has positive divisors other than 1 and itself.
Compare this number
FAQ for 1991
- Is 1991 prime?
- No
- What is the prime factorization of 1991?
- 11 × 181
- Is 1991 a perfect square?
- No
- What is 1991 in binary?
- 11111000111
- What is 1991 in Roman numerals?
- MCMXCI