11991047911 has 4 divisors (see below), whose sum is σ = 12217294152. Its totient is φ = 11764801672.

The previous prime is 11991047899. The next prime is 11991047917. The reversal of 11991047911 is 11974019911.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11974019911 = 7 ⋅1710574273.

It is a cyclic number.

It is not a de Polignac number, because 11991047911 - 2¹⁵ = 11991015143 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11991047917) 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, 113123041 + ... + 113123146.

It is an arithmetic number, because the mean of its divisors is an integer number (3054323538).

Almost surely, 2^11991047911 is an apocalyptic number.

11991047911 is a deficient number, since it is larger than the sum of its proper divisors (226246241).

11991047911 is an equidigital number, since it uses as much as digits as its factorization.

11991047911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226246240.

The product of its (nonzero) digits is 20412, while the sum is 43.

The spelling of 11991047911 in words is "eleven billion, nine hundred ninety-one million, forty-seven thousand, nine hundred eleven".