18542221 has 4 divisors (see below), whose sum is σ = 18550944. Its totient is φ = 18533500.

The previous prime is 18542201. The next prime is 18542261. The reversal of 18542221 is 12224581.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 18542221 - 2⁷ = 18542093 is a prime.

It is a super-2 number, since 2×18542221² = 687627919225682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18542201) 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, 1146 + ... + 6196.

It is an arithmetic number, because the mean of its divisors is an integer number (4637736).

Almost surely, 2^18542221 is an apocalyptic number.

It is an amenable number.

18542221 is a deficient number, since it is larger than the sum of its proper divisors (8723).

18542221 is an equidigital number, since it uses as much as digits as its factorization.

18542221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8722.

The product of its digits is 1280, while the sum is 25.

The square root of 18542221 is about 4306.0679279361. The cubic root of 18542221 is about 264.6796699031.

The spelling of 18542221 in words is "eighteen million, five hundred forty-two thousand, two hundred twenty-one".