18221338 has 8 divisors (see below), whose sum is σ = 28274580. Its totient is φ = 8796480.

The previous prime is 18221257. The next prime is 18221339. The reversal of 18221338 is 83312281.

It can be written as a sum of positive squares in 2 ways, for example, as 17749369 + 471969 = 4213^2 + 687^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (18221339) 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, 157023 + ... + 157138.

Almost surely, 2^18221338 is an apocalyptic number.

18221338 is a deficient number, since it is larger than the sum of its proper divisors (10053242).

18221338 is a wasteful number, since it uses less digits than its factorization.

18221338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314192.

The product of its digits is 2304, while the sum is 28.

The square root of 18221338 is about 4268.6459211324. The cubic root of 18221338 is about 263.1439693277.

It can be divided in two parts, 1822 and 1338, that added together give a triangular number (3160 = T₇₉).

The spelling of 18221338 in words is "eighteen million, two hundred twenty-one thousand, three hundred thirty-eight".