# 1913

This number is a prime.

The smallest prime *p* such that the next prime (1931) is a permutation of the digits of *p*. Andy Edwards introduced the name "Ormiston pairs" for these after his students at Ormiston College (in Queensland, Australia) manually inspected prime lists and found the first few cases. (An Ormiston *k*-tuple beginning with *p* is *k* consecutive primes each of whose digits are permutations of the digits of *p*.) [De Geest]

The number of letters in the chemical name for tryptophan synthetase A protein. [Byrne]

The square of 1913 and the square of its reverse have no digits in common. Are there any higher emirp pairs with this property? [Gaydos]

"The busy world, which does not hunt poets as collectors
hunt for *curios*." F. Harrison (*Webster's Revised
Unabridged Dictionary*, 1913)

The year in which mathematician Paul Erdős was born is an emirp. [Beedassy]

The first sedan-type automobile, a Hudson, went on display at the 13th National Automobile Show in New York in the emirp year 1913. [Green]

The smallest emirp such that 1913^2 +/- 90 are also emirps. [Bajpai]

The smallest Honaker prime (emirp) whose prime index is Sophie Germain prime. [Bajpai]

The smallest Honaker prime whose product of digits is a perfect cube (1*9*1*3=27=3^3). [Bajpai]

The only Honaker emirp concatenated from two double-digit primes. [Loungrides]

The smaller of two consecutive primes whose product of digits are equal and nonzero. [Gupta]

The difference between an emirp and its reverse is always divisible by 18. So is 3191 - 1913 = 71 * 18. But, 1913 is the smallest emirp such that the difference is 18 times an emirp. [Poo Sung]

Rudolf Diesel of diesel engine fame died suspiciously at sea in 1913. [Dillow]