668816851 has 2 divisors, whose sum is σ = 668816852. Its totient is φ = 668816850.

The previous prime is 668816833. The next prime is 668816857. The reversal of 668816851 is 158618866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 668816851 - 2⁹ = 668816339 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 668816795 and 668816804.

It is not a weakly prime, because it can be changed into another prime (668816857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334408425 + 334408426.

It is an arithmetic number, because the mean of its divisors is an integer number (334408426).

Almost surely, 2^668816851 is an apocalyptic number.

668816851 is a deficient number, since it is larger than the sum of its proper divisors (1).

668816851 is an equidigital number, since it uses as much as digits as its factorization.

668816851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 552960, while the sum is 49.

The square root of 668816851 is about 25861.4935956916. The cubic root of 668816851 is about 874.5186363517.

The spelling of 668816851 in words is "six hundred sixty-eight million, eight hundred sixteen thousand, eight hundred fifty-one".