1178131991 has 2 divisors, whose sum is σ = 1178131992. Its totient is φ = 1178131990.

The previous prime is 1178131961. The next prime is 1178132057. The reversal of 1178131991 is 1991318711.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1178131991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1178131901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 589065995 + 589065996.

It is an arithmetic number, because the mean of its divisors is an integer number (589065996).

Almost surely, 2^1178131991 is an apocalyptic number.

1178131991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1178131991 is an equidigital number, since it uses as much as digits as its factorization.

1178131991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 41.

The square root of 1178131991 is about 34323.9273830953. The cubic root of 1178131991 is about 1056.1638932829.

The spelling of 1178131991 in words is "one billion, one hundred seventy-eight million, one hundred thirty-one thousand, nine hundred ninety-one".