18221313 has 16 divisors (see below), whose sum is σ = 27657216. Its totient is φ = 10562640.

The previous prime is 18221257. The next prime is 18221339. The reversal of 18221313 is 31312281.

It is not a de Polignac number, because 18221313 - 2¹⁶ = 18155777 is a prime.

It is a super-3 number, since 3×18221313³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18221313.

It is not an unprimeable number, because it can be changed into a prime (18221393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11245 + ... + 12762.

It is an arithmetic number, because the mean of its divisors is an integer number (1728576).

Almost surely, 2^18221313 is an apocalyptic number.

It is an amenable number.

18221313 is a deficient number, since it is larger than the sum of its proper divisors (9435903).

18221313 is a wasteful number, since it uses less digits than its factorization.

18221313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24044.

The product of its digits is 288, while the sum is 21.

The square root of 18221313 is about 4268.6429928023. The cubic root of 18221313 is about 263.1438489816.

Adding to 18221313 its reverse (31312281), we get a palindrome (49533594).

The spelling of 18221313 in words is "eighteen million, two hundred twenty-one thousand, three hundred thirteen".