18638887 has 8 divisors (see below), whose sum is σ = 19217520. Its totient is φ = 18066240.

The previous prime is 18638863. The next prime is 18638897. The reversal of 18638887 is 78883681.

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

It is not a de Polignac number, because 18638887 - 2⁷ = 18638759 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18638887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18638897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5289 + ... + 8077.

It is an arithmetic number, because the mean of its divisors is an integer number (2402190).

Almost surely, 2^18638887 is an apocalyptic number.

18638887 is a deficient number, since it is larger than the sum of its proper divisors (578633).

18638887 is a wasteful number, since it uses less digits than its factorization.

18638887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2993.

The product of its digits is 516096, while the sum is 49.

The square root of 18638887 is about 4317.2777302370. The cubic root of 18638887 is about 265.1388236671.

The spelling of 18638887 in words is "eighteen million, six hundred thirty-eight thousand, eight hundred eighty-seven".