191819109109 has 2 divisors, whose sum is σ = 191819109110. Its totient is φ = 191819109108.

The previous prime is 191819109101. The next prime is 191819109143. The reversal of 191819109109 is 901901918191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190988228484 + 830880625 = 437022^2 + 28825^2 .

It is an emirp because it is prime and its reverse (901901918191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 191819109109 - 2³ = 191819109101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191819109101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95909554554 + 95909554555.

It is an arithmetic number, because the mean of its divisors is an integer number (95909554555).

Almost surely, 2^191819109109 is an apocalyptic number.

It is an amenable number.

191819109109 is a deficient number, since it is larger than the sum of its proper divisors (1).

191819109109 is an equidigital number, since it uses as much as digits as its factorization.

191819109109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 52488, while the sum is 49.

The spelling of 191819109109 in words is "one hundred ninety-one billion, eight hundred nineteen million, one hundred nine thousand, one hundred nine".