18717225517 has 2 divisors, whose sum is σ = 18717225518. Its totient is φ = 18717225516.

The previous prime is 18717225493. The next prime is 18717225521. The reversal of 18717225517 is 71552271781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9703432036 + 9013793481 = 98506^2 + 94941^2 .

It is an emirp because it is prime and its reverse (71552271781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18717225517 - 2¹⁵ = 18717192749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18717225217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9358612758 + 9358612759.

It is an arithmetic number, because the mean of its divisors is an integer number (9358612759).

Almost surely, 2^18717225517 is an apocalyptic number.

It is an amenable number.

18717225517 is a deficient number, since it is larger than the sum of its proper divisors (1).

18717225517 is an equidigital number, since it uses as much as digits as its factorization.

18717225517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 274400, while the sum is 46.

The spelling of 18717225517 in words is "eighteen billion, seven hundred seventeen million, two hundred twenty-five thousand, five hundred seventeen".