687791 has 8 divisors (see below), whose sum is σ = 747264. Its totient is φ = 629280.

The previous prime is 687787. The next prime is 687809. The reversal of 687791 is 197786.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 687791 - 2² = 687787 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2345 + ... + 2621.

It is an arithmetic number, because the mean of its divisors is an integer number (93408).

2⁶⁸⁷⁷⁹¹ is an apocalyptic number.

687791 is a deficient number, since it is larger than the sum of its proper divisors (59473).

687791 is a wasteful number, since it uses less digits than its factorization.

687791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481.

The product of its digits is 21168, while the sum is 38.

The square root of 687791 is about 829.3316586264. The cubic root of 687791 is about 88.2711591280.

The spelling of 687791 in words is "six hundred eighty-seven thousand, seven hundred ninety-one".