687761 has 4 divisors (see below), whose sum is σ = 689472. Its totient is φ = 686052.

The previous prime is 687749. The next prime is 687767. The reversal of 687761 is 167786.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 687761 - 2¹⁰ = 686737 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 687761.

It is not an unprimeable number, because it can be changed into a prime (687767) 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 3 ways as a sum of consecutive naturals, for example, 116 + ... + 1178.

It is an arithmetic number, because the mean of its divisors is an integer number (172368).

2⁶⁸⁷⁷⁶¹ is an apocalyptic number.

It is an amenable number.

687761 is a deficient number, since it is larger than the sum of its proper divisors (1711).

687761 is a wasteful number, since it uses less digits than its factorization.

687761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1710.

The product of its digits is 14112, while the sum is 35.

The square root of 687761 is about 829.3135715759. The cubic root of 687761 is about 88.2698757085.

The spelling of 687761 in words is "six hundred eighty-seven thousand, seven hundred sixty-one".