18156220 has 12 divisors (see below), whose sum is σ = 38128104. Its totient is φ = 7262480.

The previous prime is 18156211. The next prime is 18156227. The reversal of 18156220 is 2265181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18156227) 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 3 ways as a sum of consecutive naturals, for example, 453886 + ... + 453925.

It is an arithmetic number, because the mean of its divisors is an integer number (3177342).

Almost surely, 2^18156220 is an apocalyptic number.

18156220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18156220 is an abundant number, since it is smaller than the sum of its proper divisors (19971884).

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

18156220 is a wasteful number, since it uses less digits than its factorization.

18156220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 907820 (or 907818 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 18156220 is about 4261.0116169755. The cubic root of 18156220 is about 262.8301273545.

The spelling of 18156220 in words is "eighteen million, one hundred fifty-six thousand, two hundred twenty".