18420472 has 48 divisors (see below), whose sum is σ = 40588560. Its totient is φ = 7836864.

The previous prime is 18420433. The next prime is 18420491. The reversal of 18420472 is 27402481.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a self number, because there is not a number n which added to its sum of digits gives 18420472.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 134388 + ... + 134524.

It is an arithmetic number, because the mean of its divisors is an integer number (845595).

Almost surely, 2^18420472 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18420472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20294280).

18420472 is an abundant number, since it is smaller than the sum of its proper divisors (22168088).

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

18420472 is an frugal number, since it uses more digits than its factorization.

18420472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178 (or 146 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 18420472 is about 4291.9077343298. The cubic root of 18420472 is about 264.0990980891.

Subtracting 18420472 from its reverse (27402481), we obtain a square (8982009 = 2997²).

The spelling of 18420472 in words is "eighteen million, four hundred twenty thousand, four hundred seventy-two".