12891091 has 4 divisors (see below), whose sum is σ = 12898872. Its totient is φ = 12883312.

The previous prime is 12891061. The next prime is 12891119. The reversal of 12891091 is 19019821.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 12891091 - 2⁷ = 12890963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12891061) 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, 301 + ... + 5086.

It is an arithmetic number, because the mean of its divisors is an integer number (3224718).

Almost surely, 2^12891091 is an apocalyptic number.

12891091 is a deficient number, since it is larger than the sum of its proper divisors (7781).

12891091 is an equidigital number, since it uses as much as digits as its factorization.

12891091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7780.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 12891091 is about 3590.4165496499. The cubic root of 12891091 is about 234.4750073003.

It can be divided in two parts, 128 and 91091, that added together give a palindrome (91219).

The spelling of 12891091 in words is "twelve million, eight hundred ninety-one thousand, ninety-one".