18023221 has 2 divisors, whose sum is σ = 18023222. Its totient is φ = 18023220.

The previous prime is 18023219. The next prime is 18023263. The reversal of 18023221 is 12232081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17892900 + 130321 = 4230^2 + 361^2 .

It is a cyclic number.

It is not a de Polignac number, because 18023221 - 2¹ = 18023219 is a prime.

Together with 18023219, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18023521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9011610 + 9011611.

It is an arithmetic number, because the mean of its divisors is an integer number (9011611).

Almost surely, 2^18023221 is an apocalyptic number.

It is an amenable number.

18023221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18023221 is an equidigital number, since it uses as much as digits as its factorization.

18023221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 18023221 is about 4245.3764261841. The cubic root of 18023221 is about 262.1867877271.

The spelling of 18023221 in words is "eighteen million, twenty-three thousand, two hundred twenty-one".