18165978 has 32 divisors (see below), whose sum is σ = 40979520. Its totient is φ = 5963760.

The previous prime is 18165967. The next prime is 18165991. The reversal of 18165978 is 87956181.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1108 + ... + 6128.

It is an arithmetic number, because the mean of its divisors is an integer number (1280610).

Almost surely, 2^18165978 is an apocalyptic number.

18165978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18165978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20489760).

18165978 is an abundant number, since it is smaller than the sum of its proper divisors (22813542).

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

18165978 is a wasteful number, since it uses less digits than its factorization.

18165978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5099 (or 5093 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The square root of 18165978 is about 4262.1564964229. The cubic root of 18165978 is about 262.8772046474.

The spelling of 18165978 in words is "eighteen million, one hundred sixty-five thousand, nine hundred seventy-eight".