168509268581 has 2 divisors, whose sum is σ = 168509268582. Its totient is φ = 168509268580.

The previous prime is 168509268563. The next prime is 168509268593. The reversal of 168509268581 is 185862905861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155437005025 + 13072263556 = 394255^2 + 114334^2 .

It is a cyclic number.

It is not a de Polignac number, because 168509268581 - 2⁶ = 168509268517 is a prime.

It is a super-2 number, since 2×168509268581² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 168509268581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168509268481) 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, 84254634290 + 84254634291.

It is an arithmetic number, because the mean of its divisors is an integer number (84254634291).

Almost surely, 2^168509268581 is an apocalyptic number.

It is an amenable number.

168509268581 is a deficient number, since it is larger than the sum of its proper divisors (1).

168509268581 is an equidigital number, since it uses as much as digits as its factorization.

168509268581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8294400, while the sum is 59.

The spelling of 168509268581 in words is "one hundred sixty-eight billion, five hundred nine million, two hundred sixty-eight thousand, five hundred eighty-one".