18138517 has 2 divisors, whose sum is σ = 18138518. Its totient is φ = 18138516.

The previous prime is 18138511. The next prime is 18138539. The reversal of 18138517 is 71583181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15295921 + 2842596 = 3911^2 + 1686^2 .

It is a cyclic number.

It is not a de Polignac number, because 18138517 - 2³ = 18138509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18138511) 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, 9069258 + 9069259.

It is an arithmetic number, because the mean of its divisors is an integer number (9069259).

Almost surely, 2^18138517 is an apocalyptic number.

It is an amenable number.

18138517 is a deficient number, since it is larger than the sum of its proper divisors (1).

18138517 is an equidigital number, since it uses as much as digits as its factorization.

18138517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 34.

The square root of 18138517 is about 4258.9337867593. The cubic root of 18138517 is about 262.7446764767.

The spelling of 18138517 in words is "eighteen million, one hundred thirty-eight thousand, five hundred seventeen".