18383821 has 4 divisors (see below), whose sum is σ = 18416700. Its totient is φ = 18350944.

The previous prime is 18383803. The next prime is 18383839. The reversal of 18383821 is 12838381.

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

It is an interprime number because it is at equal distance from previous prime (18383803) and next prime (18383839).

It can be written as a sum of positive squares in 2 ways, for example, as 10465225 + 7918596 = 3235^2 + 2814^2 .

It is a cyclic number.

It is not a de Polignac number, because 18383821 - 2¹¹ = 18381773 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 (18383801) 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, 15586 + ... + 16723.

It is an arithmetic number, because the mean of its divisors is an integer number (4604175).

Almost surely, 2^18383821 is an apocalyptic number.

It is an amenable number.

18383821 is a deficient number, since it is larger than the sum of its proper divisors (32879).

18383821 is an equidigital number, since it uses as much as digits as its factorization.

18383821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32878.

The product of its digits is 9216, while the sum is 34.

The square root of 18383821 is about 4287.6358287523. The cubic root of 18383821 is about 263.9238234838.

The spelling of 18383821 in words is "eighteen million, three hundred eighty-three thousand, eight hundred twenty-one".