168281221 has 4 divisors (see below), whose sum is σ = 169003692. Its totient is φ = 167558752.

The previous prime is 168281219. The next prime is 168281227. The reversal of 168281221 is 122182861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122182861 = 53 ⋅2305337.

It can be written as a sum of positive squares in 2 ways, for example, as 72437121 + 95844100 = 8511^2 + 9790^2 .

It is a cyclic number.

It is not a de Polignac number, because 168281221 - 2¹ = 168281219 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168281227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 360886 + ... + 361351.

It is an arithmetic number, because the mean of its divisors is an integer number (42250923).

Almost surely, 2^168281221 is an apocalyptic number.

It is an amenable number.

168281221 is a deficient number, since it is larger than the sum of its proper divisors (722471).

168281221 is an equidigital number, since it uses as much as digits as its factorization.

168281221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722470.

The product of its digits is 3072, while the sum is 31.

The square root of 168281221 is about 12972.3251963555. The cubic root of 168281221 is about 552.0925475385.

The spelling of 168281221 in words is "one hundred sixty-eight million, two hundred eighty-one thousand, two hundred twenty-one".