687491 has 4 divisors (see below), whose sum is σ = 785712. Its totient is φ = 589272.

The previous prime is 687481. The next prime is 687499. The reversal of 687491 is 194786.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687491 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 687491.

It is not an unprimeable number, because it can be changed into a prime (687499) 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, 49100 + ... + 49113.

It is an arithmetic number, because the mean of its divisors is an integer number (196428).

2⁶⁸⁷⁴⁹¹ is an apocalyptic number.

687491 is a deficient number, since it is larger than the sum of its proper divisors (98221).

687491 is an equidigital number, since it uses as much as digits as its factorization.

687491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98220.

The product of its digits is 12096, while the sum is 35.

The square root of 687491 is about 829.1507703669. The cubic root of 687491 is about 88.2583232526.

The spelling of 687491 in words is "six hundred eighty-seven thousand, four hundred ninety-one".