19138890809 has 2 divisors, whose sum is σ = 19138890810. Its totient is φ = 19138890808.

The previous prime is 19138890787. The next prime is 19138890833. The reversal of 19138890809 is 90809883191.

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., 16231524409 + 2907366400 = 127403^2 + 53920^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19138890809 is a prime.

It is not a weakly prime, because it can be changed into another prime (19138890889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9569445404 + 9569445405.

It is an arithmetic number, because the mean of its divisors is an integer number (9569445405).

Almost surely, 2^19138890809 is an apocalyptic number.

It is an amenable number.

19138890809 is a deficient number, since it is larger than the sum of its proper divisors (1).

19138890809 is an equidigital number, since it uses as much as digits as its factorization.

19138890809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1119744, while the sum is 56.

The spelling of 19138890809 in words is "nineteen billion, one hundred thirty-eight million, eight hundred ninety thousand, eight hundred nine".