18084821 has 4 divisors (see below), whose sum is σ = 19148652. Its totient is φ = 17020992.

The previous prime is 18084799. The next prime is 18084851. The reversal of 18084821 is 12848081.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7102225 + 10982596 = 2665^2 + 3314^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18084821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18084851) 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, 531890 + ... + 531923.

It is an arithmetic number, because the mean of its divisors is an integer number (4787163).

Almost surely, 2^18084821 is an apocalyptic number.

It is an amenable number.

18084821 is a deficient number, since it is larger than the sum of its proper divisors (1063831).

18084821 is a wasteful number, since it uses less digits than its factorization.

18084821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1063830.

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 18084821 is about 4252.6251892214. The cubic root of 18084821 is about 262.4851498780.

The spelling of 18084821 in words is "eighteen million, eighty-four thousand, eight hundred twenty-one".