19891172249 has 16 divisors (see below), whose sum is σ = 21637929600. Its totient is φ = 18175777536.

The previous prime is 19891172209. The next prime is 19891172281. The reversal of 19891172249 is 94227119891.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19891172249 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19891172249.

It is not an unprimeable number, because it can be changed into a prime (19891172209) 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 in 15 ways as a sum of consecutive naturals, for example, 1224422 + ... + 1240560.

It is an arithmetic number, because the mean of its divisors is an integer number (1352370600).

Almost surely, 2^19891172249 is an apocalyptic number.

It is an amenable number.

19891172249 is a deficient number, since it is larger than the sum of its proper divisors (1746757351).

19891172249 is a wasteful number, since it uses less digits than its factorization.

19891172249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17104.

The product of its digits is 653184, while the sum is 53.

The spelling of 19891172249 in words is "nineteen billion, eight hundred ninety-one million, one hundred seventy-two thousand, two hundred forty-nine".