Number
1,991
1,991 is a composite number, odd, a calendar year.
Properties
- Parity
- Odd
- Digit count
- 4
- Digit sum
- 20
- Digital root
- 2
- Palindrome
- Yes
- Divisor count
- 4
- σ(n) — sum of divisors
- 2,184
Primality
Prime factorization: 11 × 181
Divisors & multiples
Aliquot sum (sum of proper divisors):
193
First multiples
Representations
- In words
- one thousand nine hundred ninety-one
- Ordinal
- 1991st
- Roman numeral
- MCMXCI
- Binary
- 11111000111
- Octal
- 3707
- Hexadecimal
- 7C7
Also seen as
Unicode codepoint
߇
U+07C7
Decimal digit (Nd)
UTF-8 encoding: DF 87 (2 bytes).
Hex color
#0007C7
RGB(0, 7, 199)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.199.