19491948809 has 2 divisors, whose sum is σ = 19491948810. Its totient is φ = 19491948808.

The previous prime is 19491948793. The next prime is 19491948841. The reversal of 19491948809 is 90884919491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18072769225 + 1419179584 = 134435^2 + 37672^2 .

It is a cyclic number.

It is not a de Polignac number, because 19491948809 - 2⁴ = 19491948793 is a prime.

It is not a weakly prime, because it can be changed into another prime (19491948869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9745974404 + 9745974405.

It is an arithmetic number, because the mean of its divisors is an integer number (9745974405).

Almost surely, 2^19491948809 is an apocalyptic number.

It is an amenable number.

19491948809 is a deficient number, since it is larger than the sum of its proper divisors (1).

19491948809 is an equidigital number, since it uses as much as digits as its factorization.

19491948809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6718464, while the sum is 62.

The spelling of 19491948809 in words is "nineteen billion, four hundred ninety-one million, nine hundred forty-eight thousand, eight hundred nine".