43661 has 2 divisors, whose sum is σ = 43662.
Its totient is φ = 43660.
The previous prime is 43651. The next prime is 43669. The reversal of 43661 is 16634.
Adding to 43661 its sum of digits (20), we get a square (43681 = 2092).
43661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 42436 + 1225 = 206^2 + 35^2
It is a cyclic number.
It is not a de Polignac number, because 43661 - 26 = 43597 is a prime.
It is a Sophie Germain prime.
It is a Chen prime.
It is a pancake number, because a pancake can be divided into 43661 parts by 295 straight cuts.
It is a Curzon number.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (43669) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21830 + 21831.
It is an arithmetic number, because the mean of its divisors is an integer number (21831).
243661 is an apocalyptic number.
It is an amenable number.
43661 is a deficient number, since it is larger than the sum of its proper divisors (1).
43661 is an equidigital number, since it uses as much as digits as its factorization.
43661 is an evil number, because the sum of its binary digits is even.
The product of its digits is 432, while the sum is 20.
The square root of 43661 is about 208.9521476319.
The cubic root of 43661 is about 35.2125837412.
The spelling of 43661 in words is "forty-three thousand, six hundred sixty-one".