18439478917 has 2 divisors, whose sum is σ = 18439478918. Its totient is φ = 18439478916.

The previous prime is 18439478903. The next prime is 18439478921. The reversal of 18439478917 is 71987493481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16281504801 + 2157974116 = 127599^2 + 46454^2 .

It is a cyclic number.

It is not a de Polignac number, because 18439478917 - 2⁷ = 18439478789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18439178917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9219739458 + 9219739459.

It is an arithmetic number, because the mean of its divisors is an integer number (9219739459).

Almost surely, 2^18439478917 is an apocalyptic number.

It is an amenable number.

18439478917 is a deficient number, since it is larger than the sum of its proper divisors (1).

18439478917 is an equidigital number, since it uses as much as digits as its factorization.

18439478917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12192768, while the sum is 61.

The spelling of 18439478917 in words is "eighteen billion, four hundred thirty-nine million, four hundred seventy-eight thousand, nine hundred seventeen".