# 1723

This number is a prime.

English broadcaster, author and parliamentarian Melvyn Bragg discussed prime numbers (like 1723 for example) during the BBC Radio 4 documentary series "In Our Time" on 12 Jan 2006.

Proving the Riemann Hypothesis is equivalent to showing floor(H(*n*)+e^{H(n))*log(H(n)}) ≥ σ(*n*), where H(*n*) = 1 + 1/2 + 1/3 + ... + 1/*n*, and
σ(*n*) is the sum of the divisors of *n*. For example, when
*n* = 17, the two sides differ by 23. [Caldwell]

The prime that splits into the two primes, 17 and 23, which are the extremal constants of the magic triangle of Yates using digits 1 through 9:

1 7 9 6 3 6 5 7 5 1 2 8 4 3 8 2 4 9[Beedassy]

The smallest distinct-digit emirp concatenated from two double-digit primes. [Loungrides]

(There are 5 curios for this number that have not yet been approved by an editor.)

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