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12891 = 34297

12891 has 4 divisors (see below), whose sum is σ = 17192. Its totient is φ = 8592.

The previous prime is 12889. The next prime is 12893. The reversal of 12891 is 19821.

12891 is digitally balanced in base 3, 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, and also an emirpimes, since its reverse is a distinct semiprime: 19821 = 36607.

It is an interprime number because it is at equal distance from previous prime (12889) and next prime (12893).

It is not a de Polignac number, because 12891 - 21 = 12889 is a prime.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (12893) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2146 + ... + 2151.

It is an arithmetic number, because the mean of its divisors is an integer number (4298).

212891 is an apocalyptic number.

12891 is a deficient number, since it is larger than the sum of its proper divisors (4301).

12891 is an equidigital number, since it uses as much as digits as its factorization.

12891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4300.

The product of its digits is 144, while the sum is 21.

The square root of 12891 is about 113.5385397123. The cubic root of 12891 is about 23.4474455568.

It can be divided in two parts, 12 and 891, that added together give a triangular number (903 = T42).

The spelling of 12891 in words is "twelve thousand, eight hundred ninety-one".

Divisors: 1 3 4297 12891