It is a happy number.
291 is nontrivially palindromic in base 9.
291 is an esthetic number in base 3 and base 16, because in such bases its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes.
It is a D-number.
It is a Duffinian number.
291 is an undulating number in base 9.
It is a plaindrome in base 11, base 14, base 15 and base 16.
It is a nialpdrome in base 8.
It is a congruent number.
291 is an equidigital number, since it uses as much as digits as its factorization.
291 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 100.
The square root of 291 is about 17.0587221092. The cubic root of 291 is about 6.6267053875.
Adding to 291 its sum of digits (12), we get a palindrome (303).
Subtracting from 291 its reverse (192), we obtain a palindrome (99).
The spelling of 291 in words is "two hundred ninety-one", and thus it is an aban number.