231 (number)

← 230 231 232 →
← 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 thirty-one
Ordinal	231st (two hundred and thirty-first)
Factorization	3 × 7 × 11
Roman numeral	CCXXXI
Binary	111001112
Ternary	221203
Quaternary	32134
Quinary	14115
Senary	10236
Octal	3478
Duodecimal	17312
Hexadecimal	E716
Vigesimal	BB20
Base 36	6F36

231 (two hundred [and] thirty-one) is the natural number following 230 and preceding 232.

In mathematics

Two hundred [and] thirty-one 231 = 3·7·11, sphenic number, triangular number, hexagonal number, octahedral number,^[1] centered octahedral number,^[2] the number of integer partitions of 16, Mertens function returns 0,^[3] and is the number of cubic inches in a U.S. liquid gallon.

In chemistry

• Ac-231 is an isotope of actinium.
• Am-231 is an artificial isotope of americium.
• Pa-231 is a naturally occurring isotope of protactinium.
• Ra-231 is an isotope of radium.
• Th-231 is an isotope of thorium.

In other fields

231 is:

• The year A.D. 231 or 231 BC.
• +231 is the country code for Liberia.
• Pacific 231, an orchestral work by French composer Arthur Honegger.
• Pacific 231, a 1949 short film directed by Jean Mitry.
• M-231 (Michigan highway), a highway in Michigan

References

1. "Sloane's A005900 : Octahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-24.
2. "Sloane's A001845 : Centered octahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-24.
3. "Sloane's A028442 : Numbers n such that Mertens' function is zero". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-24.