18656438417 has 2 divisors, whose sum is σ = 18656438418. Its totient is φ = 18656438416.

The previous prime is 18656438413. The next prime is 18656438441. The reversal of 18656438417 is 71483465681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16928872321 + 1727566096 = 130111^2 + 41564^2 .

It is a cyclic number.

It is not a de Polignac number, because 18656438417 - 2² = 18656438413 is a prime.

It is not a weakly prime, because it can be changed into another prime (18656438413) 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, 9328219208 + 9328219209.

It is an arithmetic number, because the mean of its divisors is an integer number (9328219209).

Almost surely, 2^18656438417 is an apocalyptic number.

It is an amenable number.

18656438417 is a deficient number, since it is larger than the sum of its proper divisors (1).

18656438417 is an equidigital number, since it uses as much as digits as its factorization.

18656438417 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3870720, while the sum is 53.

The spelling of 18656438417 in words is "eighteen billion, six hundred fifty-six million, four hundred thirty-eight thousand, four hundred seventeen".