1171788391 has 4 divisors (see below), whose sum is σ = 1176018952. Its totient is φ = 1167557832.

The previous prime is 1171788377. The next prime is 1171788403. The reversal of 1171788391 is 1938871711.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1171788391 - 2¹⁵ = 1171755623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1171788341) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2114865 + ... + 2115418.

It is an arithmetic number, because the mean of its divisors is an integer number (294004738).

Almost surely, 2^1171788391 is an apocalyptic number.

1171788391 is a deficient number, since it is larger than the sum of its proper divisors (4230561).

1171788391 is an equidigital number, since it uses as much as digits as its factorization.

1171788391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4230560.

The product of its digits is 84672, while the sum is 46.

The square root of 1171788391 is about 34231.3948152862. The cubic root of 1171788391 is about 1054.2648580594.

The spelling of 1171788391 in words is "one billion, one hundred seventy-one million, seven hundred eighty-eight thousand, three hundred ninety-one".