18644221 has 8 divisors (see below), whose sum is σ = 18912600. Its totient is φ = 18378048.

The previous prime is 18644203. The next prime is 18644233. The reversal of 18644221 is 12244681.

It can be written as a sum of positive squares in 4 ways, for example, as 68121 + 18576100 = 261^2 + 4310^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 18644221 - 2¹⁷ = 18513149 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18644221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18644201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22995 + ... + 23791.

It is an arithmetic number, because the mean of its divisors is an integer number (2364075).

Almost surely, 2^18644221 is an apocalyptic number.

It is an amenable number.

18644221 is a deficient number, since it is larger than the sum of its proper divisors (268379).

18644221 is a wasteful number, since it uses less digits than its factorization.

18644221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1103.

The product of its digits is 3072, while the sum is 28.

The square root of 18644221 is about 4317.8954364366. The cubic root of 18644221 is about 265.1641133675.

The spelling of 18644221 in words is "eighteen million, six hundred forty-four thousand, two hundred twenty-one".