687749 has 2 divisors, whose sum is σ = 687750. Its totient is φ = 687748.

The previous prime is 687737. The next prime is 687767. The reversal of 687749 is 947786.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 515524 + 172225 = 718^2 + 415^2 .

It is a cyclic number.

It is not a de Polignac number, because 687749 - 2¹² = 683653 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 687749.

It is not a weakly prime, because it can be changed into another prime (687779) 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, 343874 + 343875.

It is an arithmetic number, because the mean of its divisors is an integer number (343875).

2⁶⁸⁷⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

687749 is a deficient number, since it is larger than the sum of its proper divisors (1).

687749 is an equidigital number, since it uses as much as digits as its factorization.

687749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 84672, while the sum is 41.

The square root of 687749 is about 829.3063366453. The cubic root of 687749 is about 88.2693623302.

The spelling of 687749 in words is "six hundred eighty-seven thousand, seven hundred forty-nine".