18919409 has 8 divisors (see below), whose sum is σ = 20224512. Its totient is φ = 17654560.

The previous prime is 18919403. The next prime is 18919451. The reversal of 18919409 is 90491981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18919409 - 2¹⁶ = 18853873 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18919403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9089 + ... + 10974.

It is an arithmetic number, because the mean of its divisors is an integer number (2528064).

Almost surely, 2^18919409 is an apocalyptic number.

It is an amenable number.

18919409 is a deficient number, since it is larger than the sum of its proper divisors (1305103).

18919409 is a wasteful number, since it uses less digits than its factorization.

18919409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20127.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 18919409 is about 4349.6446981334. The cubic root of 18919409 is about 266.4623509619.

The spelling of 18919409 in words is "eighteen million, nine hundred nineteen thousand, four hundred nine".