688931 has 4 divisors (see below), whose sum is σ = 691152. Its totient is φ = 686712.

The previous prime is 688907. The next prime is 688939. The reversal of 688931 is 139886.

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 688931 - 2⁶ = 688867 is a prime.

It is a super-2 number, since 2×688931² = 949251845522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 688891 and 688900.

It is not an unprimeable number, because it can be changed into a prime (688939) 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, 551 + ... + 1296.

It is an arithmetic number, because the mean of its divisors is an integer number (172788).

2⁶⁸⁸⁹³¹ is an apocalyptic number.

688931 is a deficient number, since it is larger than the sum of its proper divisors (2221).

688931 is a wasteful number, since it uses less digits than its factorization.

688931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2220.

The product of its digits is 10368, while the sum is 35.

The square root of 688931 is about 830.0186744887. The cubic root of 688931 is about 88.3199014425.

The spelling of 688931 in words is "six hundred eighty-eight thousand, nine hundred thirty-one".