11556991 has 4 divisors (see below), whose sum is σ = 12236832. Its totient is φ = 10877152.

The previous prime is 11556983. The next prime is 11557037. The reversal of 11556991 is 19965511.

11556991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 11556991 - 2³ = 11556983 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 11556991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11556911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 339895 + ... + 339928.

It is an arithmetic number, because the mean of its divisors is an integer number (3059208).

Almost surely, 2^11556991 is an apocalyptic number.

11556991 is a deficient number, since it is larger than the sum of its proper divisors (679841).

11556991 is an equidigital number, since it uses as much as digits as its factorization.

11556991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 679840.

The product of its digits is 12150, while the sum is 37.

The square root of 11556991 is about 3399.5574712012. The cubic root of 11556991 is about 226.0901238178.

The spelling of 11556991 in words is "eleven million, five hundred fifty-six thousand, nine hundred ninety-one".