18947816 has 8 divisors (see below), whose sum is σ = 35527170. Its totient is φ = 9473904.

The previous prime is 18947813. The next prime is 18947827. The reversal of 18947816 is 61874981.

It can be written as a sum of positive squares in only one way, i.e., 18748900 + 198916 = 4330^2 + 446^2 .

It is a tau number, because it is divible by the number of its divisors (8).

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

It is not an unprimeable number, because it can be changed into a prime (18947813) 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 as a sum of consecutive naturals, namely, 1184231 + ... + 1184246.

Almost surely, 2^18947816 is an apocalyptic number.

It is an amenable number.

18947816 is a deficient number, since it is larger than the sum of its proper divisors (16579354).

18947816 is a wasteful number, since it uses less digits than its factorization.

18947816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2368483 (or 2368479 counting only the distinct ones).

The product of its digits is 96768, while the sum is 44.

The square root of 18947816 is about 4352.9089124400. The cubic root of 18947816 is about 266.5956463649.

The spelling of 18947816 in words is "eighteen million, nine hundred forty-seven thousand, eight hundred sixteen".