668852217221 has 2 divisors, whose sum is σ = 668852217222. Its totient is φ = 668852217220.

The previous prime is 668852217217. The next prime is 668852217239. The reversal of 668852217221 is 122712258866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644977641025 + 23874576196 = 803105^2 + 154514^2 .

It is a cyclic number.

It is not a de Polignac number, because 668852217221 - 2² = 668852217217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 668852217221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668852214221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334426108610 + 334426108611.

It is an arithmetic number, because the mean of its divisors is an integer number (334426108611).

Almost surely, 2^668852217221 is an apocalyptic number.

It is an amenable number.

668852217221 is a deficient number, since it is larger than the sum of its proper divisors (1).

668852217221 is an equidigital number, since it uses as much as digits as its factorization.

668852217221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1290240, while the sum is 50.

The spelling of 668852217221 in words is "six hundred sixty-eight billion, eight hundred fifty-two million, two hundred seventeen thousand, two hundred twenty-one".