291

291 = 3 x 97.

291 is the smallest semiprime with prime factors adding up to 100.

291 is the largest number that is not the sum of distinct non-trivial powers.

291 is 2131 in base 5. It is 10203 in base 4 and 1203 in base 6. It is 353 in base 9 (A029955) and 123 in base 16 (A048447).

Inserting a digit '1' between adjacent digits of 291 makes a prime (A050711): 21911 is prime.

291 was an arts and literary magazine published from 1915 to 1916 in New York City.

Source: Number Gossip