291 (number)

← 290 291 292 →
← 200 210 220 230 240 250 260 270 280 290 → List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred ninety-one
Ordinal	291st (two hundred ninety-first)
Factorization	3 × 97
Divisors	1, 3, 97, 291
Greek numeral	ΣϞΑ´
Roman numeral	CCXCI
Binary	1001000112
Ternary	1012103
Senary	12036
Octal	4438
Duodecimal	20312
Hexadecimal	12316

291 is the natural number following 290 and preceding 292.

In mathematics

• 291 is an odd composite number with two prime factors.^[1]
• 291 is a semiprime number meaning that it has 2 prime factors.^[2]
• 291 can be written as the sum of the nth prime plus n. It is the 52nd prime (239) plus 52.^[3]
• 291 is one of the positions of “c” in the tribonacci word abacabaab… defined by a->ab, b->ac, c->a.^[4]
• 291 is the sum of 6 different 4th powers. It is the sum of 4⁴+2⁴+2⁴+1⁴+1⁴+1⁴.^[5]

World Records

• On March 6, 2022, Tamara Walcott received the Guinness World Record for the elephant bar deadlift achieved by a woman. She lifted a weight of 291 kg.^[6]
• On December 19, 2021, the greatest number of cakes eaten online simultaneously was achieved in Tanba, Japan. There were 291 cakes.^[7]
• On October 25, 2014, the longest string instrument was created in Singapore. It was the ‘Earth Harp’ at a length of 291 m.^[8]
• On August 7, 2011, Fred Grsybowski achieved the Guinness World Record for the tallest usable pogo stick in Toronto. It was 2.91 m tall.^[9]

Other fields

• The calendar years 291 AD and 291 BC.
• 291 is the number for several highways across the countries of Canada, Japan, and the United States.
• 291 Alice is an asteroid in the asteroid belt. It was discovered by Johann Palisa in Vienna, Austria.^[10]

References

1. "Facts about the integer". mathworld.wolfram.com.
2. "Semiprime". mathworld.wolfram.com.
3. Sloane, N. J. A. (ed.). "Sequence A014688". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
4. Sloane, N. J. A. (ed.). "Sequence A003146 (Positions of letter c in the tribonacci word abacabaabacababac... generated by a->ab, b->ac, c->a (cf. A092782))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
5. Sloane, N. J. A. (ed.). "Sequence A003340 (Numbers that are the sum of 6 positive 4th powers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
6. "291 kg elephant bar deadlift". www/guinnessworldrecords.com.
7. "291 cakes eaten online". www.guinnessworldrecords.com.
8. "291 m long string instrument". www.guinnessworldrecords.com.
9. "2.91 m tall usable pogo stick". www.guinnessworldrecords.com.
10. "291 Alice". www.universguide.com. 27 March 2019.