17943991613 has 2 divisors, whose sum is σ = 17943991614. Its totient is φ = 17943991612.

The previous prime is 17943991607. The next prime is 17943991631. The reversal of 17943991613 is 31619934971.

It is a happy number.

Together with next prime (17943991631) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13708194724 + 4235796889 = 117082^2 + 65083^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-17943991613 is a prime.

It is a super-3 number, since 3×17943991613³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17943991643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8971995806 + 8971995807.

It is an arithmetic number, because the mean of its divisors is an integer number (8971995807).

Almost surely, 2^17943991613 is an apocalyptic number.

It is an amenable number.

17943991613 is a deficient number, since it is larger than the sum of its proper divisors (1).

17943991613 is an equidigital number, since it uses as much as digits as its factorization.

17943991613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1102248, while the sum is 53.

The spelling of 17943991613 in words is "seventeen billion, nine hundred forty-three million, nine hundred ninety-one thousand, six hundred thirteen".