19871191019 has 2 divisors, whose sum is σ = 19871191020. Its totient is φ = 19871191018.

The previous prime is 19871191009. The next prime is 19871191031. The reversal of 19871191019 is 91019117891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19871191019 - 2²⁰ = 19870142443 is a prime.

It is a super-2 number, since 2×19871191019² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19871191009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9935595509 + 9935595510.

It is an arithmetic number, because the mean of its divisors is an integer number (9935595510).

Almost surely, 2^19871191019 is an apocalyptic number.

19871191019 is a deficient number, since it is larger than the sum of its proper divisors (1).

19871191019 is an equidigital number, since it uses as much as digits as its factorization.

19871191019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 47.

The spelling of 19871191019 in words is "nineteen billion, eight hundred seventy-one million, one hundred ninety-one thousand, nineteen".