668221 has 2 divisors, whose sum is σ = 668222. Its totient is φ = 668220.

The previous prime is 668209. The next prime is 668243. The reversal of 668221 is 122866.

668221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 662596 + 5625 = 814^2 + 75^2 .

It is a cyclic number.

It is not a de Polignac number, because 668221 - 2⁷ = 668093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334110 + 334111.

It is an arithmetic number, because the mean of its divisors is an integer number (334111).

2⁶⁶⁸²²¹ is an apocalyptic number.

It is an amenable number.

668221 is a deficient number, since it is larger than the sum of its proper divisors (1).

668221 is an equidigital number, since it uses as much as digits as its factorization.

668221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 25.

The square root of 668221 is about 817.4478576643. The cubic root of 668221 is about 87.4258855404.

The spelling of 668221 in words is "six hundred sixty-eight thousand, two hundred twenty-one".