687979 has 4 divisors (see below), whose sum is σ = 689976. Its totient is φ = 685984.

The previous prime is 687977. The next prime is 688003. The reversal of 687979 is 979786.

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

It is a cyclic number.

It is not a de Polignac number, because 687979 - 2¹ = 687977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (687977) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 334 + ... + 1219.

It is an arithmetic number, because the mean of its divisors is an integer number (172494).

2⁶⁸⁷⁹⁷⁹ is an apocalyptic number.

687979 is a deficient number, since it is larger than the sum of its proper divisors (1997).

687979 is a wasteful number, since it uses less digits than its factorization.

687979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1996.

The product of its digits is 190512, while the sum is 46.

The square root of 687979 is about 829.4449951624. Note that the first 3 decimals coincide. The cubic root of 687979 is about 88.2792010410.

The spelling of 687979 in words is "six hundred eighty-seven thousand, nine hundred seventy-nine".