491 has 2 divisors, whose sum is σ = 492.
Its totient is φ = 490.
The previous prime is 487. The next prime is 499. The reversal of 491 is 194.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 491 - 22 = 487 is a prime.
It is a Sophie Germain prime.
It is a Chen prime.
It is a plaindrome in base 12 and base 15.
It is a nialpdrome in base 8.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 491.
It is not a weakly prime, because it can be changed into another prime (499) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245 + 246.
It is an arithmetic number, because the mean of its divisors is an integer number (246).
491 is a deficient number, since it is larger than the sum of its proper divisors (1).
491 is an equidigital number, since it uses as much as digits as its factorization.
491 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 36, while the sum is 14.
The square root of 491 is about 22.1585198062.
The cubic root of 491 is about 7.8890946040.
Adding to 491 its sum of digits (14), we get a palindrome (505).
The spelling of 491 in words is "four hundred ninety-one", and thus it is an aban number.