18918517 has 2 divisors, whose sum is σ = 18918518. Its totient is φ = 18918516.

The previous prime is 18918503. The next prime is 18918539. The reversal of 18918517 is 71581981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16313521 + 2604996 = 4039^2 + 1614^2 .

It is an emirp because it is prime and its reverse (71581981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18918517 - 2¹⁵ = 18885749 is a prime.

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 18918517.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18918577) 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, 9459258 + 9459259.

It is an arithmetic number, because the mean of its divisors is an integer number (9459259).

Almost surely, 2^18918517 is an apocalyptic number.

It is an amenable number.

18918517 is a deficient number, since it is larger than the sum of its proper divisors (1).

18918517 is an equidigital number, since it uses as much as digits as its factorization.

18918517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 40.

The square root of 18918517 is about 4349.5421598141. The cubic root of 18918517 is about 266.4581632315.

The spelling of 18918517 in words is "eighteen million, nine hundred eighteen thousand, five hundred seventeen".