491397409 has 2 divisors, whose sum is σ = 491397410. Its totient is φ = 491397408.

The previous prime is 491397367. The next prime is 491397419. The reversal of 491397409 is 904793194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 340033600 + 151363809 = 18440^2 + 12303^2 .

It is a cyclic number.

It is not a de Polignac number, because 491397409 - 2⁹ = 491396897 is a prime.

It is not a weakly prime, because it can be changed into another prime (491397419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245698704 + 245698705.

It is an arithmetic number, because the mean of its divisors is an integer number (245698705).

Almost surely, 2^491397409 is an apocalyptic number.

It is an amenable number.

491397409 is a deficient number, since it is larger than the sum of its proper divisors (1).

491397409 is an equidigital number, since it uses as much as digits as its factorization.

491397409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 244944, while the sum is 46.

The square root of 491397409 is about 22167.4854009200. The cubic root of 491397409 is about 789.1222473484.

The spelling of 491397409 in words is "four hundred ninety-one million, three hundred ninety-seven thousand, four hundred nine".