221 (number)

Source: Wikipedia, the free encyclopedia.
← 220 221 222 →
Cardinaltwo hundred twenty-one
Ordinal221st
(two hundred twenty-first)
Factorization13 × 17
Greek numeralΣΚΑ´
Roman numeralCCXXI
Binary110111012
Ternary220123
Senary10056
Octal3358
Duodecimal16512
HexadecimalDD16

221 (two hundred [and] twenty-one) is the natural number following 220 and preceding 222.

In mathematics

Its factorization as 13 × 17 makes 221 the product of two consecutive prime numbers, the sixth smallest such product.[1]

221 is a centered square number.[2]

In other fields

In

pocket aces (the strongest possible outcome in the initial deal of two cards per player) is 1/221.[3]

Sherlock Holmes's home address: 221B Baker Street.

References

  1. ^ Sloane, N. J. A. (ed.). "Sequence A006094 (Products of 2 successive primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ Sloane, N. J. A. (ed.). "Sequence A001844 (Centered square numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ISBN 9781482208948
    .
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