43561 has 8 divisors (see below), whose sum is σ = 51200. Its totient is φ = 37044.

The previous prime is 43543. The next prime is 43573. The reversal of 43561 is 16534.

It is not a de Polignac number, because 43561 - 2⁹ = 43049 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (43541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 280 + ... + 406.

It is an arithmetic number, because the mean of its divisors is an integer number (6400).

2⁴³⁵⁶¹ is an apocalyptic number.

43561 is the 121-st hex number.

It is an amenable number.

43561 is a deficient number, since it is larger than the sum of its proper divisors (7639).

43561 is an equidigital number, since it uses as much as digits as its factorization.

43561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148 (or 134 counting only the distinct ones).

The product of its digits is 360, while the sum is 19.

The square root of 43561 is about 208.7127212223. The cubic root of 43561 is about 35.1856798672.

It can be divided in two parts, 435 and 61, that added together give a triangular number (496 = T₃₁).

The spelling of 43561 in words is "forty-three thousand, five hundred sixty-one".