191 (number)

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← 190 191 192 →
Cardinal one hundred ninety-one
Ordinal 191st
(one hundred ninety-first)
Factorization prime
Prime yes
Greek numeral ΡϞΑ´
Roman numeral CXCI
Binary 101111112
Ternary 210023
Quaternary 23334
Quinary 12315
Senary 5156
Octal 2778
Duodecimal 13B12
Hexadecimal BF16
Vigesimal 9B20
Base 36 5B36

191 (one hundred [and] ninety-one) is the natural number following 190 and preceding 192.

In mathematics[edit]

In astronomy[edit]

In emergency telephone numbers[edit]

In geography[edit]

In the military[edit]

In movies[edit]

In sports[edit]

In transportation[edit]

  • RD-191, a Russian high performance single-combustion chamber rocket engine
  • 191st Street (IRT Broadway – Seventh Avenue Line), a New York City Subway station at St. Nicholas Avenue in Manhattan served by the 1 train
  • At least five known plane crashes have involved flights numbered 191; as a result, the number is considered unlucky in the airline industry and has been withdrawn from use in some airlines

In other fields[edit]

191 is also:

See also[edit]

External links[edit]


  1. ^ "Sloane's A069132 : Centered 19-gonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28. 
  2. ^ "Tables of imaginary quadratic fields with small class number". numbertheory.org.