18984809 has 4 divisors (see below), whose sum is σ = 18994320. Its totient is φ = 18975300.

The previous prime is 18984793. The next prime is 18984817. The reversal of 18984809 is 90848981.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90848981 = 43 ⋅2112767.

It is a cyclic number.

It is not a de Polignac number, because 18984809 - 2⁴ = 18984793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18984829) 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 3 ways as a sum of consecutive naturals, for example, 479 + ... + 6180.

It is an arithmetic number, because the mean of its divisors is an integer number (4748580).

Almost surely, 2^18984809 is an apocalyptic number.

It is an amenable number.

18984809 is a deficient number, since it is larger than the sum of its proper divisors (9511).

18984809 is an equidigital number, since it uses as much as digits as its factorization.

18984809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9510.

The product of its (nonzero) digits is 165888, while the sum is 47.

The square root of 18984809 is about 4357.1560678957. The cubic root of 18984809 is about 266.7690306663.

The spelling of 18984809 in words is "eighteen million, nine hundred eighty-four thousand, eight hundred nine".