18987478 has 4 divisors (see below), whose sum is σ = 28481220. Its totient is φ = 9493738.

The previous prime is 18987457. The next prime is 18987481. The reversal of 18987478 is 87478981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87478981 = 151 ⋅579331.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4746868 + ... + 4746871.

It is an arithmetic number, because the mean of its divisors is an integer number (7120305).

Almost surely, 2^18987478 is an apocalyptic number.

18987478 is a deficient number, since it is larger than the sum of its proper divisors (9493742).

18987478 is an equidigital number, since it uses as much as digits as its factorization.

18987478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9493741.

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

The square root of 18987478 is about 4357.4623348917. The cubic root of 18987478 is about 266.7815314185.

The spelling of 18987478 in words is "eighteen million, nine hundred eighty-seven thousand, four hundred seventy-eight".