18561172013 has 2 divisors, whose sum is σ = 18561172014. Its totient is φ = 18561172012.

The previous prime is 18561171943. The next prime is 18561172031. The reversal of 18561172013 is 31027116581.

Together with next prime (18561172031) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18322871044 + 238300969 = 135362^2 + 15437^2 .

It is a cyclic number.

It is not a de Polignac number, because 18561172013 - 2¹⁴ = 18561155629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18561172813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9280586006 + 9280586007.

It is an arithmetic number, because the mean of its divisors is an integer number (9280586007).

Almost surely, 2^18561172013 is an apocalyptic number.

It is an amenable number.

18561172013 is a deficient number, since it is larger than the sum of its proper divisors (1).

18561172013 is an equidigital number, since it uses as much as digits as its factorization.

18561172013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 35.

Adding to 18561172013 its reverse (31027116581), we get a palindrome (49588288594).

The spelling of 18561172013 in words is "eighteen billion, five hundred sixty-one million, one hundred seventy-two thousand, thirteen".