491495209 has 2 divisors, whose sum is σ = 491495210. Its totient is φ = 491495208.

The previous prime is 491495153. The next prime is 491495231. The reversal of 491495209 is 902594194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 490179600 + 1315609 = 22140^2 + 1147^2 .

It is a cyclic number.

It is not a de Polignac number, because 491495209 - 2²³ = 483106601 is a prime.

It is not a weakly prime, because it can be changed into another prime (491405209) 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 as a sum of consecutive naturals, namely, 245747604 + 245747605.

It is an arithmetic number, because the mean of its divisors is an integer number (245747605).

Almost surely, 2^491495209 is an apocalyptic number.

It is an amenable number.

491495209 is a deficient number, since it is larger than the sum of its proper divisors (1).

491495209 is an equidigital number, since it uses as much as digits as its factorization.

491495209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 116640, while the sum is 43.

The square root of 491495209 is about 22169.6912247329. The cubic root of 491495209 is about 789.1745953631.

The spelling of 491495209 in words is "four hundred ninety-one million, four hundred ninety-five thousand, two hundred nine".