211

This number is a prime.

+ The smallest prime Simple Mail Transfer Protocol (SMTP) reply code. It means system status, or system help reply.

+ 211 is a prime lucky number and there are 211 prime lucky numbers less than 102+1+1. [Post]

+ The smallest prime whose the reversal is simultaneously a Zuckerman and a Harshad number. [Loungrides]

+ 211 is the product of the first four primes plus one. [Patterson]

+ There are 211 stairs going from the Founder's Room to the bell chamber at Singing Tower, near Lake Wales, Florida.

+ As of September 2002, the U.S. Patent Office had exactly 211 patents in its database which contain the word 'prime' in their title. [Rupinski]

+ 3^5 - 2^5 = 211, which is prime. [La Haye]

+ The number of primes that can appear on a 24-hour digital clock (00:00 up to 23:59). [De Geest]

+ Each of the three sets of numbers that solve the minimal magic die puzzle can produce exactly 211 different patterns. [Gaydos]

+ 2-1-1 is an easy-to-remember telephone number that connects people with important community services and volunteer opportunities in the United States: http://www.211.org/. [Haga]

+ The California Penal Code section defining robbery.

+ The smallest prime formed from the reverse concatenation of three consecutive Fibonacci numbers. [Gupta]

+ The smallest prime between 2 sets of 11 consecutive composites. Note the concatenation of 2 and 11. [Opao]

+ G. H. Hardy once sent a postcard to his friend Ramanujan with a list of six New Year's resolutions beginning: (1) prove the Riemann hypothesis; (2) Make 211 not out in the fourth innings of the last Test Match at Oval; (3) ....

+ The smaller of the only two primes formed from consecutive digits repeated each-other times: one 2, two 1s. [Silva]

+ The smallest prime formed from two other primes, one of which is the sum of the digits of the other. [Silva]

+ 211 (in the 6th shell of a Modulo-40 unit circle) is congruent with the prime number 20731 (in the 519th shell of a Modulo-40 unit circle). Both primes occupy position #11 in their respective shells. [Roberts]

+ The book "211 Things A Bright Boy Can Do" by Tom Cutler is divided into handy sections.

+ Sodium benzoate (E211) can be produced by reacting sodium hydroxide with benzoic acid.

+ The minimum sum of any row, column, or diagonal, of a minimum difference prime magic square that contains the 25 primes less than 100 (Kurchan and Reed, 1994).

             41  79  17  13  61

             53  03  83  67  07

             59  97  05  23  29

             11  31  37  89  43

             47  02  71  19  73

+ A 'month of Sundays', connoting a long period of time and often regarded as the period of time for someone else to perform a task that you consider to be straightforward, is literally 211 days (7*30 + 1). The first Sunday is to occur on the first of the 211 days and the 31st Sunday occurs on the 211th day. [Green]

+ The largest known prime number that cannot be written as the sum of a prime number and a positive triangular number. [Capelle]

+ Smallest multidigit prime concatenated from the values of the distance of Fibonacci(n) to the closest prime which is not Fibonacci(n) itself. [Post]

+ The only 3-digit prime such that the sum of any two of its digits is also prime. [Green]

+ The smallest prime consisting of a prime p followed by p identical digits. [Gupta]

+ 211 is the product plus the sum of the first four non-prime numbers. [Silva]

+ 211 is formed from the last digits of the first prime number with n digits for n = 1, 2, 3. [Post]

+ Yankees star Alex Rodriguez was once suspended for 211 games. [Post]

+ 211^212-2 is the largest non-titanic prime of form p^(p+1)-2 , where p is a prime. [Loungrides]

+ The Cleavers lived at 211 Pine Street for most of the television series "Leave It to Beaver." [Gaydos]

+ Emmanuel Vantieghem found a solved Sudoku containing 211 distinct primes in traditional word search format: up, down, forward, backward, or diagonal.

4  5  9  1  6  7  3  2  8
3  1  2  5  8  9  6  7  4
8  6  7  2  3  4  1  5  9
9  7  4  6  5  3  2  8  1
5  8  3  9  1  2  4  6  7
6  2  1  7  4  8  9  3  5
1  9  5  8  2  6  7  4  3
2  3  8  4  7  1  5  9  6
7  4  6  3  9  5  8  1  2
Is 211 the limit?

+ Is 211 the largest prime that is not the sum of prime and a triangular number? [Bergot]

+ The smallest number n for which the sum of the first n Honaker primes (4293721) and the sum of their prime indices (473761) are both prime numbers with the same sum of digits (28). [Gaydos]

+ The smallest prime whose resersal is the sum of consecutive primes (53 + 59). [Silva]

+ The Kennel Club recognizes 211 dog breeds. [Clark]

+ The smallest prime whose reversal is an abundant number. [Loungrides]

+ There are 211 cases of the product of a prime number and its prime index having distinct digits. [Gaydos]

+ The only 3-digit prime whose the sum of any two of its digits is prime. [Loungrides]

+ In police code, 211 stands for robbery (perhaps by a cat burglar) in progress. Note the con-cat-enation of two primes: 2 and 11. [Reynolds]

+ If A = 1, B = 2, C = 3, ..., Z = 26, then "CHRISTOPHER CALDWELL" is prime. [Homewood]

+ The idea to create a "random number” sequence by utilizing the primes occurred during the reading of The Mathematical Experience by Philip J. Davis & Reuben Hersh (1981), on page 211. Honaker numbers are named in honor of Swiss-German immigrant Hans Jacob Honaker who came to America in the 1700s.

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