12891691 has 4 divisors (see below), whose sum is σ = 13307584. Its totient is φ = 12475800.

The previous prime is 12891653. The next prime is 12891713. The reversal of 12891691 is 19619821.

12891691 is digitally balanced in base 2, 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 a de Polignac number, because none of the positive numbers 2^k-12891691 is a prime.

It is the 3591-st Hogben number.

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 12891691.

It is not an unprimeable number, because it can be changed into a prime (12891601) by changing a digit.

It is a nontrivial repunit in base 3590.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207900 + ... + 207961.

It is an arithmetic number, because the mean of its divisors is an integer number (3326896).

Almost surely, 2^12891691 is an apocalyptic number.

12891691 is a deficient number, since it is larger than the sum of its proper divisors (415893).

12891691 is an equidigital number, since it uses as much as digits as its factorization.

12891691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415892.

The product of its digits is 7776, while the sum is 37.

The square root of 12891691 is about 3590.5001044423. The cubic root of 12891691 is about 234.4786450276.

It can be divided in two parts, 128 and 91691, that added together give a palindrome (91819).

The spelling of 12891691 in words is "twelve million, eight hundred ninety-one thousand, six hundred ninety-one".