18478987 has 4 divisors (see below), whose sum is σ = 18929736. Its totient is φ = 18028240.

The previous prime is 18478973. The next prime is 18479009. The reversal of 18478987 is 78987481.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18478987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18478487) 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, 225313 + ... + 225394.

It is an arithmetic number, because the mean of its divisors is an integer number (4732434).

Almost surely, 2^18478987 is an apocalyptic number.

18478987 is a deficient number, since it is larger than the sum of its proper divisors (450749).

18478987 is an equidigital number, since it uses as much as digits as its factorization.

18478987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450748.

The product of its digits is 903168, while the sum is 52.

The square root of 18478987 is about 4298.7192278631. The cubic root of 18478987 is about 264.3784507557.

The spelling of 18478987 in words is "eighteen million, four hundred seventy-eight thousand, nine hundred eighty-seven".