12181591 has 4 divisors (see below), whose sum is σ = 12232800. Its totient is φ = 12130384.

The previous prime is 12181579. The next prime is 12181607. The reversal of 12181591 is 19518121.

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 12181591 - 2⁹ = 12181079 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 (12181531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25246 + ... + 25723.

It is an arithmetic number, because the mean of its divisors is an integer number (3058200).

Almost surely, 2^12181591 is an apocalyptic number.

12181591 is a deficient number, since it is larger than the sum of its proper divisors (51209).

12181591 is an equidigital number, since it uses as much as digits as its factorization.

12181591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51208.

The product of its digits is 720, while the sum is 28.

The square root of 12181591 is about 3490.2136037784. The cubic root of 12181591 is about 230.0919040406.

It can be divided in two parts, 1218 and 1591, that added together give a square (2809 = 53²).

The spelling of 12181591 in words is "twelve million, one hundred eighty-one thousand, five hundred ninety-one".