168905221 has 4 divisors (see below), whose sum is σ = 168931692. Its totient is φ = 168878752.

The previous prime is 168905213. The next prime is 168905257. The reversal of 168905221 is 122509861.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 83064996 + 85840225 = 9114^2 + 9265^2 .

It is a cyclic number.

It is not a de Polignac number, because 168905221 - 2³ = 168905213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168905291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2865 + ... + 18601.

It is an arithmetic number, because the mean of its divisors is an integer number (42232923).

Almost surely, 2^168905221 is an apocalyptic number.

It is an amenable number.

168905221 is a deficient number, since it is larger than the sum of its proper divisors (26471).

168905221 is a wasteful number, since it uses less digits than its factorization.

168905221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26470.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 168905221 is about 12996.3541426048. The cubic root of 168905221 is about 552.7741066662.

The spelling of 168905221 in words is "one hundred sixty-eight million, nine hundred five thousand, two hundred twenty-one".