668448817 has 2 divisors, whose sum is σ = 668448818. Its totient is φ = 668448816.

The previous prime is 668448787. The next prime is 668448863. The reversal of 668448817 is 718844866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 497780721 + 170668096 = 22311^2 + 13064^2 .

It is a cyclic number.

It is not a de Polignac number, because 668448817 - 2⁷ = 668448689 is a prime.

It is a super-4 number, since 4×668448817⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 3.

It is not a weakly prime, because it can be changed into another prime (668448017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334224408 + 334224409.

It is an arithmetic number, because the mean of its divisors is an integer number (334224409).

Almost surely, 2^668448817 is an apocalyptic number.

It is an amenable number.

668448817 is a deficient number, since it is larger than the sum of its proper divisors (1).

668448817 is an equidigital number, since it uses as much as digits as its factorization.

668448817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2064384, while the sum is 52.

The square root of 668448817 is about 25854.3771342494. The cubic root of 668448817 is about 874.3581979869.

The spelling of 668448817 in words is "six hundred sixty-eight million, four hundred forty-eight thousand, eight hundred seventeen".