18947321 has 2 divisors, whose sum is σ = 18947322. Its totient is φ = 18947320.

The previous prime is 18947311. The next prime is 18947339. The reversal of 18947321 is 12374981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18181696 + 765625 = 4264^2 + 875^2 .

It is an emirp because it is prime and its reverse (12374981) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18947321 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18947311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9473660 + 9473661.

It is an arithmetic number, because the mean of its divisors is an integer number (9473661).

Almost surely, 2^18947321 is an apocalyptic number.

It is an amenable number.

18947321 is a deficient number, since it is larger than the sum of its proper divisors (1).

18947321 is an equidigital number, since it uses as much as digits as its factorization.

18947321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 18947321 is about 4352.8520535392. The cubic root of 18947321 is about 266.5933247958.

The spelling of 18947321 in words is "eighteen million, nine hundred forty-seven thousand, three hundred twenty-one".