18017920 has 64 divisors (see below), whose sum is σ = 44064000. Its totient is φ = 7042048.

The previous prime is 18017917. The next prime is 18017929. The reversal of 18017920 is 2971081.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×18017920² = 649290882252800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18017929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29781 + ... + 30379.

It is an arithmetic number, because the mean of its divisors is an integer number (688500).

Almost surely, 2^18017920 is an apocalyptic number.

18017920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18017920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22032000).

18017920 is an abundant number, since it is smaller than the sum of its proper divisors (26046080).

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

18017920 is an equidigital number, since it uses as much as digits as its factorization.

18017920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665 (or 653 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 18017920 is about 4244.7520540074. The cubic root of 18017920 is about 262.1610803642.

The spelling of 18017920 in words is "eighteen million, seventeen thousand, nine hundred twenty".