18987816 has 16 divisors (see below), whose sum is σ = 47469600. Its totient is φ = 6329264.

The previous prime is 18987803. The next prime is 18987853. The reversal of 18987816 is 61878981.

It is an alternating number because its digits alternate between odd and even.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 395556 + ... + 395603.

It is an arithmetic number, because the mean of its divisors is an integer number (2966850).

Almost surely, 2^18987816 is an apocalyptic number.

It is an amenable number.

18987816 is an abundant number, since it is smaller than the sum of its proper divisors (28481784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18987816 is a wasteful number, since it uses less digits than its factorization.

18987816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 791168 (or 791164 counting only the distinct ones).

The product of its digits is 193536, while the sum is 48.

The square root of 18987816 is about 4357.5011187606. The cubic root of 18987816 is about 266.7831144201.

The spelling of 18987816 in words is "eighteen million, nine hundred eighty-seven thousand, eight hundred sixteen".