12991591 has 4 divisors (see below), whose sum is σ = 13169632. Its totient is φ = 12813552.

The previous prime is 12991571. The next prime is 12991603. The reversal of 12991591 is 19519921.

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 12991591 - 2²¹ = 10894439 is a prime.

It is a super-2 number, since 2×12991591² = 337562873422562, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 12991591.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12991541) 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, 88911 + ... + 89056.

It is an arithmetic number, because the mean of its divisors is an integer number (3292408).

Almost surely, 2^12991591 is an apocalyptic number.

12991591 is a deficient number, since it is larger than the sum of its proper divisors (178041).

12991591 is an equidigital number, since it uses as much as digits as its factorization.

12991591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178040.

The product of its digits is 7290, while the sum is 37.

The square root of 12991591 is about 3604.3849683406. The cubic root of 12991591 is about 235.0827594435.

The spelling of 12991591 in words is "twelve million, nine hundred ninety-one thousand, five hundred ninety-one".