18989878 has 4 divisors (see below), whose sum is σ = 28484820. Its totient is φ = 9494938.

The previous prime is 18989863. The next prime is 18989879. The reversal of 18989878 is 87898981.

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

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18989879) 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, 4747468 + ... + 4747471.

It is an arithmetic number, because the mean of its divisors is an integer number (7121205).

Almost surely, 2^18989878 is an apocalyptic number.

18989878 is a deficient number, since it is larger than the sum of its proper divisors (9494942).

18989878 is an equidigital number, since it uses as much as digits as its factorization.

18989878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9494941.

The product of its digits is 2322432, while the sum is 58.

The square root of 18989878 is about 4357.7377158338. The cubic root of 18989878 is about 266.7927712595.

The spelling of 18989878 in words is "eighteen million, nine hundred eighty-nine thousand, eight hundred seventy-eight".