668216789 has 2 divisors, whose sum is σ = 668216790. Its totient is φ = 668216788.

The previous prime is 668216779. The next prime is 668216803. The reversal of 668216789 is 987612866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 441714289 + 226502500 = 21017^2 + 15050^2 .

It is a cyclic number.

It is not a de Polignac number, because 668216789 - 2²⁴ = 651439573 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 668216789.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668216779) 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, 334108394 + 334108395.

It is an arithmetic number, because the mean of its divisors is an integer number (334108395).

Almost surely, 2^668216789 is an apocalyptic number.

It is an amenable number.

668216789 is a deficient number, since it is larger than the sum of its proper divisors (1).

668216789 is an equidigital number, since it uses as much as digits as its factorization.

668216789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1741824, while the sum is 53.

The square root of 668216789 is about 25849.8895355473. The cubic root of 668216789 is about 874.2570189302.

The spelling of 668216789 in words is "six hundred sixty-eight million, two hundred sixteen thousand, seven hundred eighty-nine".