9801 (nine thousand eight hundred [and] one) is the natural number following 9800 and preceding 9802.
In mathematics 9801 is most notable for being the third, and only 4-digit square pentagonal number, since 9801 is a square number, which can be written as: , and it is also a pentagonal number, since it can also be written as: . 9801 is also the number that is below 10,000 which are integral multiples of their reversals. The only other number which has this property is 8712. 9801 is the sixth number such as the binomial coefficient is a perfect square. 9801 is a part of one of the first few pairs of consecutive powerful numbers with 9800. (9800, 9801)
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