18443909 has 6 divisors (see below), whose sum is σ = 20273190. Its totient is φ = 16767080.

The previous prime is 18443879. The next prime is 18443923. The reversal of 18443909 is 90934481.

It can be written as a sum of positive squares in only one way, i.e., 14822500 + 3621409 = 3850^2 + 1903^2 .

It is not a de Polignac number, because 18443909 - 2⁸ = 18443653 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18443969) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 76094 + ... + 76335.

It is an arithmetic number, because the mean of its divisors is an integer number (3378865).

Almost surely, 2^18443909 is an apocalyptic number.

It is an amenable number.

18443909 is a deficient number, since it is larger than the sum of its proper divisors (1829281).

18443909 is a wasteful number, since it uses less digits than its factorization.

18443909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152451 (or 152440 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 38.

The square root of 18443909 is about 4294.6372372996. The cubic root of 18443909 is about 264.2110580739.

The spelling of 18443909 in words is "eighteen million, four hundred forty-three thousand, nine hundred nine".