43891 has 2 divisors, whose sum is σ = 43892. Its totient is φ = 43890.

The previous prime is 43889. The next prime is 43913. The reversal of 43891 is 19834.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 43891 - 2¹ = 43889 is a prime.

Together with 43889, it forms a pair of twin primes.

It is the 210-th Hogben number.

43891 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (43801) by changing a digit.

It is a nontrivial repunit in base 209.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21945 + 21946.

It is an arithmetic number, because the mean of its divisors is an integer number (21946).

2⁴³⁸⁹¹ is an apocalyptic number.

43891 is the 133-rd centered pentagonal number.

43891 is a deficient number, since it is larger than the sum of its proper divisors (1).

43891 is an equidigital number, since it uses as much as digits as its factorization.

43891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 25.

The square root of 43891 is about 209.5017899685. The cubic root of 43891 is about 35.2743071287.

It can be divided in two parts, 438 and 91, that added together give a square (529 = 23²).

The spelling of 43891 in words is "forty-three thousand, eight hundred ninety-one".