11566991 has 4 divisors (see below), whose sum is σ = 12175800. Its totient is φ = 10958184.

The previous prime is 11566949. The next prime is 11566993. The reversal of 11566991 is 19966511.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11566991 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 (11566993) 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, 304376 + ... + 304413.

It is an arithmetic number, because the mean of its divisors is an integer number (3043950).

Almost surely, 2^11566991 is an apocalyptic number.

11566991 is a deficient number, since it is larger than the sum of its proper divisors (608809).

11566991 is an equidigital number, since it uses as much as digits as its factorization.

11566991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 608808.

The product of its digits is 14580, while the sum is 38.

The square root of 11566991 is about 3401.0279328462. The cubic root of 11566991 is about 226.1553152230.

The spelling of 11566991 in words is "eleven million, five hundred sixty-six thousand, nine hundred ninety-one".