1191688889 has 4 divisors (see below), whose sum is σ = 1193141220. Its totient is φ = 1190236560.

The previous prime is 1191688871. The next prime is 1191688931. The reversal of 1191688889 is 9888861911.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9888861911 = 59 ⋅167607829.

It can be written as a sum of positive squares in 2 ways, for example, as 108160000 + 1083528889 = 10400^2 + 32917^2 .

It is a cyclic number.

It is not a de Polignac number, because 1191688889 - 2⁸ = 1191688633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1191684889) 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 3 ways as a sum of consecutive naturals, for example, 724934 + ... + 726575.

It is an arithmetic number, because the mean of its divisors is an integer number (298285305).

Almost surely, 2^1191688889 is an apocalyptic number.

It is an amenable number.

1191688889 is a deficient number, since it is larger than the sum of its proper divisors (1452331).

1191688889 is an equidigital number, since it uses as much as digits as its factorization.

1191688889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1452330.

The product of its digits is 1990656, while the sum is 59.

The square root of 1191688889 is about 34520.8471651551. The cubic root of 1191688889 is about 1060.1995853563.

The spelling of 1191688889 in words is "one billion, one hundred ninety-one million, six hundred eighty-eight thousand, eight hundred eighty-nine".