668779289 has 2 divisors, whose sum is σ = 668779290. Its totient is φ = 668779288.

The previous prime is 668779283. The next prime is 668779339. The reversal of 668779289 is 982977866.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 391723264 + 277056025 = 19792^2 + 16645^2 .

It is a cyclic number.

It is not a de Polignac number, because 668779289 - 2⁴ = 668779273 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (668779283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334389644 + 334389645.

It is an arithmetic number, because the mean of its divisors is an integer number (334389645).

Almost surely, 2^668779289 is an apocalyptic number.

It is an amenable number.

668779289 is a deficient number, since it is larger than the sum of its proper divisors (1).

668779289 is an equidigital number, since it uses as much as digits as its factorization.

668779289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18289152, while the sum is 62.

The square root of 668779289 is about 25860.7673706717. The cubic root of 668779289 is about 874.5022645134.

The spelling of 668779289 in words is "six hundred sixty-eight million, seven hundred seventy-nine thousand, two hundred eighty-nine".