18903221 has 2 divisors, whose sum is σ = 18903222. Its totient is φ = 18903220.

The previous prime is 18903197. The next prime is 18903251. The reversal of 18903221 is 12230981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17522596 + 1380625 = 4186^2 + 1175^2 .

It is a cyclic number.

It is not a de Polignac number, because 18903221 - 2¹⁰ = 18902197 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18903251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9451610 + 9451611.

It is an arithmetic number, because the mean of its divisors is an integer number (9451611).

Almost surely, 2^18903221 is an apocalyptic number.

It is an amenable number.

18903221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18903221 is an equidigital number, since it uses as much as digits as its factorization.

18903221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 18903221 is about 4347.7834582693. The cubic root of 18903221 is about 266.3863316145.

The spelling of 18903221 in words is "eighteen million, nine hundred three thousand, two hundred twenty-one".