11991871 has 4 divisors (see below), whose sum is σ = 12083544. Its totient is φ = 11900200.

The previous prime is 11991839. The next prime is 11991911. The reversal of 11991871 is 17819911.

11991871 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 11991871 - 2⁵ = 11991839 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 11991871.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11991271) 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, 45640 + ... + 45901.

It is an arithmetic number, because the mean of its divisors is an integer number (3020886).

Almost surely, 2^11991871 is an apocalyptic number.

11991871 is a deficient number, since it is larger than the sum of its proper divisors (91673).

11991871 is an equidigital number, since it uses as much as digits as its factorization.

11991871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91672.

The product of its digits is 4536, while the sum is 37.

The square root of 11991871 is about 3462.9280962792. The cubic root of 11991871 is about 228.8911402658.

The spelling of 11991871 in words is "eleven million, nine hundred ninety-one thousand, eight hundred seventy-one".