678735509 has 2 divisors, whose sum is σ = 678735510. Its totient is φ = 678735508.

The previous prime is 678735467. The next prime is 678735569. The reversal of 678735509 is 905537876.

It is a happy number.

678735509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 626100484 + 52635025 = 25022^2 + 7255^2 .

It is a cyclic number.

It is not a de Polignac number, because 678735509 - 2¹⁶ = 678669973 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (678735569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339367754 + 339367755.

It is an arithmetic number, because the mean of its divisors is an integer number (339367755).

Almost surely, 2^678735509 is an apocalyptic number.

It is an amenable number.

678735509 is a deficient number, since it is larger than the sum of its proper divisors (1).

678735509 is an equidigital number, since it uses as much as digits as its factorization.

678735509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1587600, while the sum is 50.

The square root of 678735509 is about 26052.5528307688. The cubic root of 678735509 is about 878.8205225378.

The spelling of 678735509 in words is "six hundred seventy-eight million, seven hundred thirty-five thousand, five hundred nine".