688581 has 10 divisors (see below), whose sum is σ = 1028742. Its totient is φ = 459000.

The previous prime is 688573. The next prime is 688591. The reversal of 688581 is 185886.

It can be written as a sum of positive squares in only one way, i.e., 443556 + 245025 = 666^2 + 495^2 .

It is not a de Polignac number, because 688581 - 2³ = 688573 is a prime.

It is a super-2 number, since 2×688581² = 948287587122, which contains 22 as substring.

688581 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 688581.

It is not an unprimeable number, because it can be changed into a prime (688511) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4170 + ... + 4331.

2⁶⁸⁸⁵⁸¹ is an apocalyptic number.

It is an amenable number.

688581 is a deficient number, since it is larger than the sum of its proper divisors (340161).

688581 is an equidigital number, since it uses as much as digits as its factorization.

688581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8513 (or 8504 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 688581 is about 829.8078090739. The cubic root of 688581 is about 88.3049424206.

It can be divided in two parts, 68 and 8581, that added together give a square (8649 = 93²).

The spelling of 688581 in words is "six hundred eighty-eight thousand, five hundred eighty-one".