43691 has 2 divisors, whose sum is σ = 43692. Its totient is φ = 43690.

The previous prime is 43669. The next prime is 43711. The reversal of 43691 is 19634.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 43691 - 2⁶ = 43627 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is the 17-th Jacobsthal number.

It is a plaindrome in base 4 and base 16.

It is not a weakly prime, because it can be changed into another prime (43651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21845 + 21846.

It is an arithmetic number, because the mean of its divisors is an integer number (21846).

43691 is a Friedman number, since it can be written as (4^9+3-1)/6, using all its digits and the basic arithmetic operations.

2⁴³⁶⁹¹ is an apocalyptic number.

43691 is a deficient number, since it is larger than the sum of its proper divisors (1).

43691 is an equidigital number, since it uses as much as digits as its factorization.

43691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 23.

The square root of 43691 is about 209.0239220759. The cubic root of 43691 is about 35.2206468918.

The spelling of 43691 in words is "forty-three thousand, six hundred ninety-one".