43721 has 2 divisors, whose sum is σ = 43722.
Its totient is φ = 43720.
The previous prime is 43717. The next prime is 43753. The reversal of 43721 is 12734.
It can be divided in two parts, 4 and 3721, that multiplied together give a square (14884 = 1222).
It is a happy number.
43721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 40000 + 3721 = 200^2 + 61^2
It is a cyclic number.
It is not a de Polignac number, because 43721 - 22 = 43717 is a prime.
It is a Sophie Germain prime.
It is a Chen prime.
It is the 38-th Perrin number.
It is a Curzon number.
It is a self number, because there is not a number n which added to its sum of digits gives 43721.
It is not a weakly prime, because it can be changed into another prime (43711) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21860 + 21861.
It is an arithmetic number, because the mean of its divisors is an integer number (21861).
243721 is an apocalyptic number.
It is an amenable number.
43721 is a deficient number, since it is larger than the sum of its proper divisors (1).
43721 is an equidigital number, since it uses as much as digits as its factorization.
43721 is an evil number, because the sum of its binary digits is even.
The product of its digits is 168, while the sum is 17.
The square root of 43721 is about 209.0956718825.
The cubic root of 43721 is about 35.2287063523.
The spelling of 43721 in words is "forty-three thousand, seven hundred twenty-one", and thus it is an iban number.