687641 has 2 divisors, whose sum is σ = 687642. Its totient is φ = 687640.

The previous prime is 687637. The next prime is 687647. The reversal of 687641 is 146786.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 687241 + 400 = 829^2 + 20^2 .

It is a cyclic number.

It is not a de Polignac number, because 687641 - 2² = 687637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 687598 and 687607.

It is not a weakly prime, because it can be changed into another prime (687647) 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 as a sum of consecutive naturals, namely, 343820 + 343821.

It is an arithmetic number, because the mean of its divisors is an integer number (343821).

2⁶⁸⁷⁶⁴¹ is an apocalyptic number.

It is an amenable number.

687641 is a deficient number, since it is larger than the sum of its proper divisors (1).

687641 is an equidigital number, since it uses as much as digits as its factorization.

687641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 32.

The square root of 687641 is about 829.2412194289. The cubic root of 687641 is about 88.2647416570.

The spelling of 687641 in words is "six hundred eighty-seven thousand, six hundred forty-one".