Term

Right-Truncatable Prime

Primes that stay prime as you delete digits from the right (3797 → 379 → 37 → 3). There are exactly 83.

58 numbers tagged.

A right-truncatable prime stays prime every time you chop off its last digit: 3797 → 379 → 37 → 3, all prime. There are exactly 83 of them in base 10, the largest being 73,939,133.

They form a finite tree rooted at the single-digit primes 2, 3, 5, 7, where each child appends a digit that keeps the number prime — and the tree simply runs out. Its companion is the [[left-truncatable-prime]].

2 3 5 7 23 29 31 37 53 59 71 73 79 233 239 293 311 313 317 373 379 593 599 719 733 739 797 2,333 2,339 2,393 2,399 2,939 3,119 3,137 3,733 3,739 3,793 3,797 5,939 7,193 7,331 7,333 7,393 23,333 23,339 23,399 23,993 29,399 31,193 31,379 37,337 37,339 37,397 59,393 59,399 71,933 73,331 73,939

← all tags