18940425209 has 2 divisors, whose sum is σ = 18940425210. Its totient is φ = 18940425208.

The previous prime is 18940425191. The next prime is 18940425211. The reversal of 18940425209 is 90252404981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16110717184 + 2829708025 = 126928^2 + 53195^2 .

It is an emirp because it is prime and its reverse (90252404981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18940425209 - 2¹⁶ = 18940359673 is a prime.

Together with 18940425211, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18940425209.

It is not a weakly prime, because it can be changed into another prime (18940425109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9470212604 + 9470212605.

It is an arithmetic number, because the mean of its divisors is an integer number (9470212605).

Almost surely, 2^18940425209 is an apocalyptic number.

It is an amenable number.

18940425209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18940425209 is an equidigital number, since it uses as much as digits as its factorization.

18940425209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 207360, while the sum is 44.

The spelling of 18940425209 in words is "eighteen billion, nine hundred forty million, four hundred twenty-five thousand, two hundred nine".