11811591 has 24 divisors (see below), whose sum is σ = 18729360. Its totient is φ = 7113600.

The previous prime is 11811587. The next prime is 11811599. The reversal of 11811591 is 19511811.

11811591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11811591 - 2² = 11811587 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11811599) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22411 + ... + 22931.

It is an arithmetic number, because the mean of its divisors is an integer number (780390).

Almost surely, 2^11811591 is an apocalyptic number.

11811591 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

11811591 is a deficient number, since it is larger than the sum of its proper divisors (6917769).

11811591 is a wasteful number, since it uses less digits than its factorization.

11811591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 767 (or 764 counting only the distinct ones).

The product of its digits is 360, while the sum is 27.

The square root of 11811591 is about 3436.7995286313. The cubic root of 11811591 is about 227.7383309220.

It can be divided in two parts, 1181 and 1591, that added together give a palindrome (2772).

The spelling of 11811591 in words is "eleven million, eight hundred eleven thousand, five hundred ninety-one".