11520547991 has 4 divisors (see below), whose sum is σ = 11548716000. Its totient is φ = 11492379984.

The previous prime is 11520547979. The next prime is 11520548029. The reversal of 11520547991 is 19974502511.

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-11520547991 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 (11520547921) 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, 14083391 + ... + 14084208.

It is an arithmetic number, because the mean of its divisors is an integer number (2887179000).

Almost surely, 2^11520547991 is an apocalyptic number.

11520547991 is a deficient number, since it is larger than the sum of its proper divisors (28168009).

11520547991 is an equidigital number, since it uses as much as digits as its factorization.

11520547991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28168008.

The product of its (nonzero) digits is 113400, while the sum is 44.

The spelling of 11520547991 in words is "eleven billion, five hundred twenty million, five hundred forty-seven thousand, nine hundred ninety-one".