18216978 has 16 divisors (see below), whose sum is σ = 39236736. Its totient is φ = 5605200.

The previous prime is 18216973. The next prime is 18217019. The reversal of 18216978 is 87961281.

It is not an unprimeable number, because it can be changed into a prime (18216971) 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 in 7 ways as a sum of consecutive naturals, for example, 116698 + ... + 116853.

It is an arithmetic number, because the mean of its divisors is an integer number (2452296).

Almost surely, 2^18216978 is an apocalyptic number.

18216978 is an abundant number, since it is smaller than the sum of its proper divisors (21019758).

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

18216978 is a wasteful number, since it uses less digits than its factorization.

18216978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233569.

The product of its digits is 48384, while the sum is 42.

The square root of 18216978 is about 4268.1351899864. The cubic root of 18216978 is about 263.1229792989.

The spelling of 18216978 in words is "eighteen million, two hundred sixteen thousand, nine hundred seventy-eight".