688724 has 6 divisors (see below), whose sum is σ = 1205274. Its totient is φ = 344360.

The previous prime is 688717. The next prime is 688729. The reversal of 688724 is 427886.

It can be written as a sum of positive squares in only one way, i.e., 669124 + 19600 = 818^2 + 140^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (688729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86087 + ... + 86094.

It is an arithmetic number, because the mean of its divisors is an integer number (200879).

2⁶⁸⁸⁷²⁴ is an apocalyptic number.

It is an amenable number.

688724 is a deficient number, since it is larger than the sum of its proper divisors (516550).

688724 is a wasteful number, since it uses less digits than its factorization.

688724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172185 (or 172183 counting only the distinct ones).

The product of its digits is 21504, while the sum is 35.

The square root of 688724 is about 829.8939691310. The cubic root of 688724 is about 88.3110548618.

The spelling of 688724 in words is "six hundred eighty-eight thousand, seven hundred twenty-four".