18353821 has 4 divisors (see below), whose sum is σ = 18535644. Its totient is φ = 18172000.

The previous prime is 18353789. The next prime is 18353831. The reversal of 18353821 is 12835381.

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 10982596 + 7371225 = 3314^2 + 2715^2 .

It is a cyclic number.

It is not a de Polignac number, because 18353821 - 2⁵ = 18353789 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 (18353831) 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, 90760 + ... + 90961.

It is an arithmetic number, because the mean of its divisors is an integer number (4633911).

Almost surely, 2^18353821 is an apocalyptic number.

It is an amenable number.

18353821 is a deficient number, since it is larger than the sum of its proper divisors (181823).

18353821 is a wasteful number, since it uses less digits than its factorization.

18353821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181822.

The product of its digits is 5760, while the sum is 31.

The square root of 18353821 is about 4284.1359688973. The cubic root of 18353821 is about 263.7801822261.

The spelling of 18353821 in words is "eighteen million, three hundred fifty-three thousand, eight hundred twenty-one".