681609 has 8 divisors (see below), whose sum is σ = 916480. Its totient is φ = 450576.

The previous prime is 681607. The next prime is 681613. The reversal of 681609 is 906186.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 681609 - 2¹ = 681607 is a prime.

It is a Duffinian number.

681609 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (681607) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 514 + ... + 1275.

It is an arithmetic number, because the mean of its divisors is an integer number (114560).

2⁶⁸¹⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

681609 is a deficient number, since it is larger than the sum of its proper divisors (234871).

681609 is a wasteful number, since it uses less digits than its factorization.

681609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1919.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 681609 is about 825.5961482468. The cubic root of 681609 is about 88.0058966434.

The spelling of 681609 in words is "six hundred eighty-one thousand, six hundred nine".