689681 has 4 divisors (see below), whose sum is σ = 726000. Its totient is φ = 653364.

The previous prime is 689641. The next prime is 689693. The reversal of 689681 is 186986.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 186986 = 2 ⋅93493.

It is a cyclic number.

It is not a de Polignac number, because 689681 - 2¹⁰ = 688657 is a prime.

It is a super-2 number, since 2×689681² = 951319763522, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (689621) 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 in 3 ways as a sum of consecutive naturals, for example, 18131 + ... + 18168.

It is an arithmetic number, because the mean of its divisors is an integer number (181500).

2⁶⁸⁹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

689681 is a deficient number, since it is larger than the sum of its proper divisors (36319).

689681 is a wasteful number, since it uses less digits than its factorization.

689681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36318.

The product of its digits is 20736, while the sum is 38.

The square root of 689681 is about 830.4703486579. The cubic root of 689681 is about 88.3519394373.

The spelling of 689681 in words is "six hundred eighty-nine thousand, six hundred eighty-one".