18421806 has 32 divisors (see below), whose sum is σ = 40360320. Its totient is φ = 5570784.

The previous prime is 18421801. The next prime is 18421813. The reversal of 18421806 is 60812481.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18421801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2601 + ... + 6603.

It is an arithmetic number, because the mean of its divisors is an integer number (1261260).

Almost surely, 2^18421806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18421806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20180160).

18421806 is an abundant number, since it is smaller than the sum of its proper divisors (21938514).

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

18421806 is a wasteful number, since it uses less digits than its factorization.

18421806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4080.

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 18421806 is about 4292.0631402625. The cubic root of 18421806 is about 264.1054732368.

The spelling of 18421806 in words is "eighteen million, four hundred twenty-one thousand, eight hundred six".