18221413 has 4 divisors (see below), whose sum is σ = 20824480. Its totient is φ = 15618348.

The previous prime is 18221407. The next prime is 18221417. The reversal of 18221413 is 31412281.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31412281 = 821 ⋅38261.

It is a cyclic number.

It is not a de Polignac number, because 18221413 - 2¹⁷ = 18090341 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 (18221417) 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, 1301523 + ... + 1301536.

It is an arithmetic number, because the mean of its divisors is an integer number (5206120).

Almost surely, 2^18221413 is an apocalyptic number.

It is an amenable number.

18221413 is a deficient number, since it is larger than the sum of its proper divisors (2603067).

18221413 is an equidigital number, since it uses as much as digits as its factorization.

18221413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2603066.

The product of its digits is 384, while the sum is 22.

The square root of 18221413 is about 4268.6547061106. The cubic root of 18221413 is about 263.1443303654.

Adding to 18221413 its reverse (31412281), we get a palindrome (49633694).

The spelling of 18221413 in words is "eighteen million, two hundred twenty-one thousand, four hundred thirteen".