18987494 has 4 divisors (see below), whose sum is σ = 28481244. Its totient is φ = 9493746.

The previous prime is 18987491. The next prime is 18987497. The reversal of 18987494 is 49478981.

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

It is an interprime number because it is at equal distance from previous prime (18987491) and next prime (18987497).

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 (18987491) by changing a digit.

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, 4746872 + ... + 4746875.

It is an arithmetic number, because the mean of its divisors is an integer number (7120311).

Almost surely, 2^18987494 is an apocalyptic number.

18987494 is a deficient number, since it is larger than the sum of its proper divisors (9493750).

18987494 is an equidigital number, since it uses as much as digits as its factorization.

18987494 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9493749.

The product of its digits is 580608, while the sum is 50.

The square root of 18987494 is about 4357.4641708223. The cubic root of 18987494 is about 266.7816063539.

The spelling of 18987494 in words is "eighteen million, nine hundred eighty-seven thousand, four hundred ninety-four".