18613217081 has 2 divisors, whose sum is σ = 18613217082. Its totient is φ = 18613217080.

The previous prime is 18613217071. The next prime is 18613217099. The reversal of 18613217081 is 18071231681.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15956742400 + 2656474681 = 126320^2 + 51541^2 .

It is a cyclic number.

It is not a de Polignac number, because 18613217081 - 2⁶ = 18613217017 is a prime.

It is a super-2 number, since 2×18613217081² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18613217071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9306608540 + 9306608541.

It is an arithmetic number, because the mean of its divisors is an integer number (9306608541).

Almost surely, 2^18613217081 is an apocalyptic number.

It is an amenable number.

18613217081 is a deficient number, since it is larger than the sum of its proper divisors (1).

18613217081 is an equidigital number, since it uses as much as digits as its factorization.

18613217081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 38.

The spelling of 18613217081 in words is "eighteen billion, six hundred thirteen million, two hundred seventeen thousand, eighty-one".