16685186868509 has 2 divisors, whose sum is σ = 16685186868510. Its totient is φ = 16685186868508.

The previous prime is 16685186868481. The next prime is 16685186868529. The reversal of 16685186868509 is 90586868158661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8499848702500 + 8185338166009 = 2915450^2 + 2861003^2 .

It is a cyclic number.

It is not a de Polignac number, because 16685186868509 - 2³⁶ = 16616467391773 is a prime.

It is a super-3 number, since 3×16685186868509³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16685186868509.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16685186868529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8342593434254 + 8342593434255.

It is an arithmetic number, because the mean of its divisors is an integer number (8342593434255).

Almost surely, 2^{16685186868509} is an apocalyptic number.

It is an amenable number.

16685186868509 is a deficient number, since it is larger than the sum of its proper divisors (1).

16685186868509 is an equidigital number, since it uses as much as digits as its factorization.

16685186868509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1194393600, while the sum is 77.

The spelling of 16685186868509 in words is "sixteen trillion, six hundred eighty-five billion, one hundred eighty-six million, eight hundred sixty-eight thousand, five hundred nine".