491186809 has 4 divisors (see below), whose sum is σ = 495693220. Its totient is φ = 486680400.

The previous prime is 491186783. The next prime is 491186819. The reversal of 491186809 is 908681194.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 174240000 + 316946809 = 13200^2 + 17803^2 .

It is a cyclic number.

It is not a de Polignac number, because 491186809 - 2⁷ = 491186681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (491186819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2253042 + ... + 2253259.

It is an arithmetic number, because the mean of its divisors is an integer number (123923305).

Almost surely, 2^491186809 is an apocalyptic number.

It is an amenable number.

491186809 is a deficient number, since it is larger than the sum of its proper divisors (4506411).

491186809 is a wasteful number, since it uses less digits than its factorization.

491186809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4506410.

The product of its (nonzero) digits is 124416, while the sum is 46.

The square root of 491186809 is about 22162.7346913688. The cubic root of 491186809 is about 789.0094988958.

The spelling of 491186809 in words is "four hundred ninety-one million, one hundred eighty-six thousand, eight hundred nine".