18663509 has 2 divisors, whose sum is σ = 18663510. Its totient is φ = 18663508.

The previous prime is 18663481. The next prime is 18663523. The reversal of 18663509 is 90536681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17247409 + 1416100 = 4153^2 + 1190^2 .

It is an emirp because it is prime and its reverse (90536681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18663509 - 2¹² = 18659413 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 (18663109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9331754 + 9331755.

It is an arithmetic number, because the mean of its divisors is an integer number (9331755).

Almost surely, 2^18663509 is an apocalyptic number.

It is an amenable number.

18663509 is a deficient number, since it is larger than the sum of its proper divisors (1).

18663509 is an equidigital number, since it uses as much as digits as its factorization.

18663509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 18663509 is about 4320.1283545747. The cubic root of 18663509 is about 265.2555219016.

The spelling of 18663509 in words is "eighteen million, six hundred sixty-three thousand, five hundred nine".