17818149581 has 2 divisors, whose sum is σ = 17818149582. Its totient is φ = 17818149580.

The previous prime is 17818149571. The next prime is 17818149689. The reversal of 17818149581 is 18594181871.

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., 12142938025 + 5675211556 = 110195^2 + 75334^2 .

It is a cyclic number.

It is not a de Polignac number, because 17818149581 - 2²² = 17813955277 is a prime.

It is a super-2 number, since 2×17818149581² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17818149551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8909074790 + 8909074791.

It is an arithmetic number, because the mean of its divisors is an integer number (8909074791).

Almost surely, 2^17818149581 is an apocalyptic number.

It is an amenable number.

17818149581 is a deficient number, since it is larger than the sum of its proper divisors (1).

17818149581 is an equidigital number, since it uses as much as digits as its factorization.

17818149581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 645120, while the sum is 53.

The spelling of 17818149581 in words is "seventeen billion, eight hundred eighteen million, one hundred forty-nine thousand, five hundred eighty-one".