216678689 has 2 divisors, whose sum is σ = 216678690. Its totient is φ = 216678688.

The previous prime is 216678647. The next prime is 216678701. The reversal of 216678689 is 986876612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 216678400 + 289 = 14720^2 + 17^2 .

It is a cyclic number.

It is not a de Polignac number, because 216678689 - 2⁸ = 216678433 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 216678689.

It is not a weakly prime, because it can be changed into another prime (216678629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108339344 + 108339345.

It is an arithmetic number, because the mean of its divisors is an integer number (108339345).

Almost surely, 2^216678689 is an apocalyptic number.

It is an amenable number.

216678689 is a deficient number, since it is larger than the sum of its proper divisors (1).

216678689 is an equidigital number, since it uses as much as digits as its factorization.

216678689 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 216678689 is about 14720.0098165728. The cubic root of 216678689 is about 600.6277587100.

The spelling of 216678689 in words is "two hundred sixteen million, six hundred seventy-eight thousand, six hundred eighty-nine".