18978 has 8 divisors (see below), whose sum is σ = 37968. Its totient is φ = 6324.

The previous prime is 18973. The next prime is 18979. The reversal of 18978 is 87981.

It is a sphenic number, since it is the product of 3 distinct primes.

18978 is an admirable number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18973) by changing a digit.

18978 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1576 + ... + 1587.

It is an arithmetic number, because the mean of its divisors is an integer number (4746).

2¹⁸⁹⁷⁸ is an apocalyptic number.

18978 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18984).

18978 is a wasteful number, since it uses less digits than its factorization.

18978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3168.

The product of its digits is 4032, while the sum is 33.

The square root of 18978 is about 137.7606620193. The cubic root of 18978 is about 26.6737134155.

The spelling of 18978 in words is "eighteen thousand, nine hundred seventy-eight".