687679 has 2 divisors, whose sum is σ = 687680. Its totient is φ = 687678.

The previous prime is 687647. The next prime is 687683. The reversal of 687679 is 976786.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 687679 - 2⁵ = 687647 is a prime.

687679 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343839 + 343840.

It is an arithmetic number, because the mean of its divisors is an integer number (343840).

2⁶⁸⁷⁶⁷⁹ is an apocalyptic number.

687679 is a deficient number, since it is larger than the sum of its proper divisors (1).

687679 is an equidigital number, since it uses as much as digits as its factorization.

687679 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 43.

The square root of 687679 is about 829.2641316251. The cubic root of 687679 is about 88.2663675046.

The spelling of 687679 in words is "six hundred eighty-seven thousand, six hundred seventy-nine".