18218773 has 4 divisors (see below), whose sum is σ = 18227340. Its totient is φ = 18210208.

The previous prime is 18218771. The next prime is 18218779. The reversal of 18218773 is 37781281.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 3526884 + 14691889 = 1878^2 + 3833^2 .

It is a cyclic number.

It is not a de Polignac number, because 18218773 - 2¹ = 18218771 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 (18218771) 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, 1611 + ... + 6247.

It is an arithmetic number, because the mean of its divisors is an integer number (4556835).

Almost surely, 2^18218773 is an apocalyptic number.

It is an amenable number.

18218773 is a deficient number, since it is larger than the sum of its proper divisors (8567).

18218773 is an equidigital number, since it uses as much as digits as its factorization.

18218773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8566.

The product of its digits is 18816, while the sum is 37.

The square root of 18218773 is about 4268.3454639942. The cubic root of 18218773 is about 263.1316212415.

It can be divided in two parts, 18 and 218773, that added together give a triangular number (218791 = T₆₆₁).

The spelling of 18218773 in words is "eighteen million, two hundred eighteen thousand, seven hundred seventy-three".