1191118861 has 2 divisors, whose sum is σ = 1191118862. Its totient is φ = 1191118860.

The previous prime is 1191118853. The next prime is 1191118867. The reversal of 1191118861 is 1688111911.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 732730761 + 458388100 = 27069^2 + 21410^2 .

It is an emirp because it is prime and its reverse (1688111911) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1988111611 and 1161118891.

It is a cyclic number.

It is not a de Polignac number, because 1191118861 - 2³ = 1191118853 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1191118861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1191118867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 595559430 + 595559431.

It is an arithmetic number, because the mean of its divisors is an integer number (595559431).

Almost surely, 2^1191118861 is an apocalyptic number.

It is an amenable number.

1191118861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1191118861 is an equidigital number, since it uses as much as digits as its factorization.

1191118861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 37.

The square root of 1191118861 is about 34512.5898912267. The cubic root of 1191118861 is about 1060.0305144295.

The spelling of 1191118861 in words is "one billion, one hundred ninety-one million, one hundred eighteen thousand, eight hundred sixty-one".