491071813 has 2 divisors, whose sum is σ = 491071814. Its totient is φ = 491071812.

The previous prime is 491071811. The next prime is 491071831. The reversal of 491071813 is 318170194.

Together with next prime (491071831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 423454084 + 67617729 = 20578^2 + 8223^2 .

It is a cyclic number.

It is not a de Polignac number, because 491071813 - 2¹ = 491071811 is a prime.

Together with 491071811, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (491071811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245535906 + 245535907.

It is an arithmetic number, because the mean of its divisors is an integer number (245535907).

Almost surely, 2^491071813 is an apocalyptic number.

It is an amenable number.

491071813 is a deficient number, since it is larger than the sum of its proper divisors (1).

491071813 is an equidigital number, since it uses as much as digits as its factorization.

491071813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 491071813 is about 22160.1401845746. The cubic root of 491071813 is about 788.9479201398.

The spelling of 491071813 in words is "four hundred ninety-one million, seventy-one thousand, eight hundred thirteen".