18218813 has 4 divisors (see below), whose sum is σ = 18475488. Its totient is φ = 17962140.

The previous prime is 18218807. The next prime is 18218819. The reversal of 18218813 is 31881281.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (18218807) and next prime (18218819).

It is a cyclic number.

It is not a de Polignac number, because 18218813 - 2⁴ = 18218797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18218813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18218819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128231 + ... + 128372.

It is an arithmetic number, because the mean of its divisors is an integer number (4618872).

Almost surely, 2^18218813 is an apocalyptic number.

It is an amenable number.

18218813 is a deficient number, since it is larger than the sum of its proper divisors (256675).

18218813 is an equidigital number, since it uses as much as digits as its factorization.

18218813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256674.

The product of its digits is 3072, while the sum is 32.

The square root of 18218813 is about 4268.3501496480. The cubic root of 18218813 is about 263.1318138132.

The spelling of 18218813 in words is "eighteen million, two hundred eighteen thousand, eight hundred thirteen".