688091 has 4 divisors (see below), whose sum is σ = 718032. Its totient is φ = 658152.

The previous prime is 688087. The next prime is 688097. The reversal of 688091 is 190886.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190886 = 2 ⋅95443.

It is a cyclic number.

It is not a de Polignac number, because 688091 - 2² = 688087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (688097) 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, 14936 + ... + 14981.

It is an arithmetic number, because the mean of its divisors is an integer number (179508).

2⁶⁸⁸⁰⁹¹ is an apocalyptic number.

688091 is a deficient number, since it is larger than the sum of its proper divisors (29941).

688091 is a wasteful number, since it uses less digits than its factorization.

688091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29940.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 688091 is about 829.5125074404. The cubic root of 688091 is about 88.2839912715.

The spelling of 688091 in words is "six hundred eighty-eight thousand, ninety-one".