231 (number)

← 230 231 232 →
← 230 231 232 233 234 235 236 237 238 239 → List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred thirty-one
Ordinal	231st (two hundred thirty-first)
Factorization	3 × 7 × 11
Greek numeral	ΣΛΑ´
Roman numeral	CCXXXI, ccxxxi
Binary	111001112
Ternary	221203
Senary	10236
Octal	3478
Duodecimal	17312
Hexadecimal	E716

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

Mathematics

• 231 is a sphenic number.
• 231 is the 21st triangular number, ^[1] a doubly triangular number, a hexagonal number, an octahedral number ^[2] and a centered octahedral number. ^[3]
• 231 is palindromic in base 2 (11100111₂).
• 231 is the number of integer partitions of 16.
• The Mertens function of 231 returns 0. ^[4]

In other fields

• A US gallon is defined by being exactly 231 cubic inches, the volume of a cylinder 7 inches in diameter and 6 inches tall, where ${\displaystyle \pi }$ is approximated as ${\displaystyle {\frac {22}{7}}}$.

Religion

• 231 in the Kabbalistic text Sefer Yetzirah is identified as the number of “gates” in the Hebrew alphabet, mystical combinations of two unique letters where order is interchangeable.

References

1. "A000217 - OEIS". oeis.org. Retrieved 2024-11-28.
2. "Sloane's A005900 : Octahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-24.
3. "Sloane's A001845 : Centered octahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-24.
4. "Sloane's A028442 : Numbers n such that Mertens' function is zero". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-24.