687778 has 16 divisors (see below), whose sum is σ = 1270080. Its totient is φ = 272016.

The previous prime is 687773. The next prime is 687779. The reversal of 687778 is 877786.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687773) 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 in 7 ways as a sum of consecutive naturals, for example, 1708 + ... + 2071.

It is an arithmetic number, because the mean of its divisors is an integer number (79380).

2⁶⁸⁷⁷⁷⁸ is an apocalyptic number.

687778 is a deficient number, since it is larger than the sum of its proper divisors (582302).

687778 is a wasteful number, since it uses less digits than its factorization.

687778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3801.

The product of its digits is 131712, while the sum is 43.

The square root of 687778 is about 829.3238209529. The cubic root of 687778 is about 88.2706029841.

The spelling of 687778 in words is "six hundred eighty-seven thousand, seven hundred seventy-eight".