43909 has 4 divisors (see below), whose sum is σ = 46240. Its totient is φ = 41580.

The previous prime is 43891. The next prime is 43913. The reversal of 43909 is 90934.

43909 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 43909 - 2⁷ = 43781 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 (43969) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1137 + ... + 1174.

It is an arithmetic number, because the mean of its divisors is an integer number (11560).

2⁴³⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

43909 is a deficient number, since it is larger than the sum of its proper divisors (2331).

43909 is a wasteful number, since it uses less digits than its factorization.

43909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2330.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 43909 is about 209.5447446251. The cubic root of 43909 is about 35.2791285480.

Adding to 43909 its sum of digits (25), we get a palindrome (43934).

The spelling of 43909 in words is "forty-three thousand, nine hundred nine".