18712409 has 4 divisors (see below), whose sum is σ = 19526016. Its totient is φ = 17898804.

The previous prime is 18712403. The next prime is 18712411. The reversal of 18712409 is 90421781.

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 an emirpimes, since its reverse is a distinct semiprime: 90421781 = 137 ⋅660013.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18712409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18712403) 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, 406769 + ... + 406814.

It is an arithmetic number, because the mean of its divisors is an integer number (4881504).

Almost surely, 2^18712409 is an apocalyptic number.

It is an amenable number.

18712409 is a deficient number, since it is larger than the sum of its proper divisors (813607).

18712409 is an equidigital number, since it uses as much as digits as its factorization.

18712409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813606.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 18712409 is about 4325.7842063607. The cubic root of 18712409 is about 265.4869839685.

The spelling of 18712409 in words is "eighteen million, seven hundred twelve thousand, four hundred nine".