231 (number)

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, a doubly triangular number, a hexagonal number, an octahedral number and a centered octahedral number.
• 231 is palindromic in base 2 (11100111₂).
• 231 is the number of integer partitions of 16.
• The Mertens function of 231 returns 0.

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 is approximated as .

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