18813321 has 12 divisors (see below), whose sum is σ = 27327300. Its totient is φ = 12471840.

The previous prime is 18813313. The next prime is 18813329. The reversal of 18813321 is 12331881.

It is an interprime number because it is at equal distance from previous prime (18813313) and next prime (18813329).

It can be written as a sum of positive squares in 2 ways, for example, as 8643600 + 10169721 = 2940^2 + 3189^2 .

It is not a de Polignac number, because 18813321 - 2³ = 18813313 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18813329) 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 11 ways as a sum of consecutive naturals, for example, 4146 + ... + 7403.

It is an arithmetic number, because the mean of its divisors is an integer number (2277275).

Almost surely, 2^18813321 is an apocalyptic number.

It is an amenable number.

18813321 is a deficient number, since it is larger than the sum of its proper divisors (8513979).

18813321 is a wasteful number, since it uses less digits than its factorization.

18813321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11736 (or 11733 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 18813321 is about 4337.4325354984. The cubic root of 18813321 is about 265.9633667304.

The spelling of 18813321 in words is "eighteen million, eight hundred thirteen thousand, three hundred twenty-one".