As of August 2014, only the first five repunits, through (10^1031-1)/9, have been proved prime. The last four repunits are known only to be probable primes ...

In recreational mathematics, a repunit is a number like 11, 111, or 1111 that contains only the digit 1 — a more specific type of repdigit.

1031. This number is a prime. + The number of ones ... (The next few that could possibly be prime are those with 49081, 86453, 109297, and 270343 digits.).

A repunit prime is a repunit (i.e., a number consisting of copies of the single digit 1) that is also a prime number. ... , 19, 23, 317, and 1031, 49081, 86453, ...

... 1031 ones. However, in 1999 and 2000 respectively strings consisting of 49081 and 86453 ones were found to be probable primes, which means that although ...

2013/03/22 · Repunit primes in base 10 appear to be fewer, with only seven known as of 2006, for n n taking on the values 2, 19, 23, 317, 1031, 49081, 86453 ...

For both (10^p-1)/9 & (10^p+1)/11 to be primes, we need to check the primality of (10^p+1)/11 for p=2, 19, 23, 317, 1031, 49081, 86453, and 109297. On checking, ...

2008/09/06 · ... 1031... After that the next numbers likely to be prime are R49081 and R86453, then R109297 and R270343. [Due to computing limitations ...

A circular prime only consists of the digits 1, 3, 7 and 9. The single-digit primes 2 and 5 are the only exceptions.

Apart from these 9 prime permutable numbers, all the remaining numbers have an odd number of digits: 1, 2, 3, 19, 23, 317, 1031, 49081, 86453, 109297, 270343, ...