687647 has 2 divisors, whose sum is σ = 687648. Its totient is φ = 687646.

The previous prime is 687641. The next prime is 687679. The reversal of 687647 is 746786.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687647 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 687647.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343823 + 343824.

It is an arithmetic number, because the mean of its divisors is an integer number (343824).

2⁶⁸⁷⁶⁴⁷ is an apocalyptic number.

687647 is a deficient number, since it is larger than the sum of its proper divisors (1).

687647 is an equidigital number, since it uses as much as digits as its factorization.

687647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 38.

The square root of 687647 is about 829.2448371862. The cubic root of 687647 is about 88.2649983737.

The spelling of 687647 in words is "six hundred eighty-seven thousand, six hundred forty-seven".