678388691 has 2 divisors, whose sum is σ = 678388692. Its totient is φ = 678388690.

The previous prime is 678388651. The next prime is 678388759. The reversal of 678388691 is 196883876.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 678388691 - 2¹⁰ = 678387667 is a prime.

It is a super-2 number, since 2×678388691² = 920422432153386962, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (678388651) 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, 339194345 + 339194346.

It is an arithmetic number, because the mean of its divisors is an integer number (339194346).

Almost surely, 2^678388691 is an apocalyptic number.

678388691 is a deficient number, since it is larger than the sum of its proper divisors (1).

678388691 is an equidigital number, since it uses as much as digits as its factorization.

678388691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3483648, while the sum is 56.

The square root of 678388691 is about 26045.8958571211. The cubic root of 678388691 is about 878.6708114449.

The spelling of 678388691 in words is "six hundred seventy-eight million, three hundred eighty-eight thousand, six hundred ninety-one".