18939443 has 2 divisors, whose sum is σ = 18939444. Its totient is φ = 18939442.

The previous prime is 18939439. The next prime is 18939457. The reversal of 18939443 is 34493981.

It is a weak prime.

It is an emirp because it is prime and its reverse (34493981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18939443 - 2² = 18939439 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18939443.

It is not a weakly prime, because it can be changed into another prime (18939043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9469721 + 9469722.

It is an arithmetic number, because the mean of its divisors is an integer number (9469722).

Almost surely, 2^18939443 is an apocalyptic number.

18939443 is a deficient number, since it is larger than the sum of its proper divisors (1).

18939443 is an equidigital number, since it uses as much as digits as its factorization.

18939443 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 41.

The square root of 18939443 is about 4351.9470355233. The cubic root of 18939443 is about 266.5563712275.

The spelling of 18939443 in words is "eighteen million, nine hundred thirty-nine thousand, four hundred forty-three".