221 (two hundred ndtwenty-one) is the natural number following

220 __NOTOC__ Year 220 ( CCXX) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Antonius and Eutychianus (or, less frequently, year 973 '' ...

and preceding

222 __NOTOC__ Year 222 (Roman numerals, CCXXII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Antoninus and Severus (or, less ...

In mathematics

Its factorization as 13 × 17 makes 221 the product of two consecutive

prime number A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only way ...

s, the sixth smallest such product. 221 is a

centered square number In elementary number theory, a centered square number is a centered figurate number that gives the number of dots in a square with a dot in the center and all other dots surrounding the center dot in successive square layers. That is, each c ...

In other fields

Texas hold 'em Texas hold 'em (also known as Texas holdem, hold 'em, and holdem) is one of the most popular variants of the card game of poker. Two cards, known as hole cards, are dealt face down to each player, and then five community cards are dealt fa ...

, the probability of being dealt pocket aces (the strongest possible outcome in the initial deal of two cards per player) is 1/221. Sherlock Holmes's home address:

221B Baker Street 221B Baker Street is the London address of the fictional detective Sherlock Holmes, created by author Sir Arthur Conan Doyle. In the United Kingdom, postal addresses with a number followed by a letter may indicate a separate address within a ...

References

{{DEFAULTSORT:221 (Number) Integers