18708768217 has 2 divisors, whose sum is σ = 18708768218. Its totient is φ = 18708768216.

The previous prime is 18708768163. The next prime is 18708768233. The reversal of 18708768217 is 71286780781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14703017536 + 4005750681 = 121256^2 + 63291^2 .

It is an emirp because it is prime and its reverse (71286780781) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18708768217 is a prime.

It is not a weakly prime, because it can be changed into another prime (18708763217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9354384108 + 9354384109.

It is an arithmetic number, because the mean of its divisors is an integer number (9354384109).

Almost surely, 2^18708768217 is an apocalyptic number.

It is an amenable number.

18708768217 is a deficient number, since it is larger than the sum of its proper divisors (1).

18708768217 is an equidigital number, since it uses as much as digits as its factorization.

18708768217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2107392, while the sum is 55.

The spelling of 18708768217 in words is "eighteen billion, seven hundred eight million, seven hundred sixty-eight thousand, two hundred seventeen".