18904909 has 2 divisors, whose sum is σ = 18904910. Its totient is φ = 18904908.

The previous prime is 18904889. The next prime is 18904913. The reversal of 18904909 is 90940981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14402025 + 4502884 = 3795^2 + 2122^2 .

It is an emirp because it is prime and its reverse (90940981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18904909 - 2⁹ = 18904397 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 (18904939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9452454 + 9452455.

It is an arithmetic number, because the mean of its divisors is an integer number (9452455).

Almost surely, 2^18904909 is an apocalyptic number.

It is an amenable number.

18904909 is a deficient number, since it is larger than the sum of its proper divisors (1).

18904909 is an equidigital number, since it uses as much as digits as its factorization.

18904909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 18904909 is about 4347.9775758391. The cubic root of 18904909 is about 266.3942605409.

The spelling of 18904909 in words is "eighteen million, nine hundred four thousand, nine hundred nine".