18509473 has 2 divisors, whose sum is σ = 18509474. Its totient is φ = 18509472.

The previous prime is 18509471. The next prime is 18509497. The reversal of 18509473 is 37490581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18421264 + 88209 = 4292^2 + 297^2 .

It is an emirp because it is prime and its reverse (37490581) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18509473 - 2¹ = 18509471 is a prime.

Together with 18509471, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18509471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9254736 + 9254737.

It is an arithmetic number, because the mean of its divisors is an integer number (9254737).

Almost surely, 2^18509473 is an apocalyptic number.

It is an amenable number.

18509473 is a deficient number, since it is larger than the sum of its proper divisors (1).

18509473 is an equidigital number, since it uses as much as digits as its factorization.

18509473 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 18509473 is about 4302.2637064690. The cubic root of 18509473 is about 264.5237583823.

The spelling of 18509473 in words is "eighteen million, five hundred nine thousand, four hundred seventy-three".