25821

25821 is a number that falls between 25820 and 25822 in the sequence of natural numbers. It is an odd number, as it cannot be evenly divided by 2. In the decimal numeral system, it is written as "twenty-five thousand, eight hundred twenty-one." In Roman numerals, it is represented as MMDCCCXXI.

The number 25821 has some interesting properties in mathematics. For instance, it is a composite number, meaning it has factors other than 1 and itself. Its prime factorization is 3 times 8607, indicating that it is not a prime number. Additionally, 25821 is a hexagonal number, which means it can be represented as a regular hexagon with 25821 dots.

In recreational mathematics, 25821 is known for being the smallest number that can be expressed as the sum of two positive cubes in two different ways: 25821 = 28^3 + 1^3 = 27^3 + 12^3. This property makes it a part of the taxonomy of numbers that are sums of cubes.

The number 25821 does not hold any significant historical or cultural importance, but it serves as a useful example in various mathematical contexts. Its properties make it a subject of interest for mathematicians and enthusiasts alike.