491388261649 has 2 divisors, whose sum is σ = 491388261650. Its totient is φ = 491388261648.

The previous prime is 491388261643. The next prime is 491388261779. The reversal of 491388261649 is 946162883194.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 293825791249 + 197562470400 = 542057^2 + 444480^2 .

It is a cyclic number.

It is not a de Polignac number, because 491388261649 - 2⁹ = 491388261137 is a prime.

It is not a weakly prime, because it can be changed into another prime (491388261643) 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, 245694130824 + 245694130825.

It is an arithmetic number, because the mean of its divisors is an integer number (245694130825).

Almost surely, 2^491388261649 is an apocalyptic number.

It is an amenable number.

491388261649 is a deficient number, since it is larger than the sum of its proper divisors (1).

491388261649 is an equidigital number, since it uses as much as digits as its factorization.

491388261649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17915904, while the sum is 61.

The spelling of 491388261649 in words is "four hundred ninety-one billion, three hundred eighty-eight million, two hundred sixty-one thousand, six hundred forty-nine".