18009220 has 12 divisors (see below), whose sum is σ = 37819404. Its totient is φ = 7203680.

The previous prime is 18009197. The next prime is 18009223. The reversal of 18009220 is 2290081.

It can be written as a sum of positive squares in 2 ways, for example, as 9622404 + 8386816 = 3102^2 + 2896^2 .

It is a junction number, because it is equal to n+sod(n) for n = 18009191 and 18009200.

It is not an unprimeable number, because it can be changed into a prime (18009223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 450211 + ... + 450250.

It is an arithmetic number, because the mean of its divisors is an integer number (3151617).

Almost surely, 2^18009220 is an apocalyptic number.

18009220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18009220 is an abundant number, since it is smaller than the sum of its proper divisors (19810184).

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

18009220 is a wasteful number, since it uses less digits than its factorization.

18009220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 900470 (or 900468 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 18009220 is about 4243.7271354318. The cubic root of 18009220 is about 262.1188785157.

The spelling of 18009220 in words is "eighteen million, nine thousand, two hundred twenty".