689731 has 4 divisors (see below), whose sum is σ = 788272. Its totient is φ = 591192.

The previous prime is 689723. The next prime is 689761. The reversal of 689731 is 137986.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 137986 = 2 ⋅68993.

It is not a de Polignac number, because 689731 - 2³ = 689723 is a prime.

It is a super-2 number, since 2×689731² = 951457704722, which contains 22 as substring.

It is the 831-st Hogben number.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is a zygodrome in base 6.

It is not an unprimeable number, because it can be changed into a prime (689761) by changing a digit.

It is a nontrivial repunit in base 830.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49260 + ... + 49273.

It is an arithmetic number, because the mean of its divisors is an integer number (197068).

2⁶⁸⁹⁷³¹ is an apocalyptic number.

689731 is a deficient number, since it is larger than the sum of its proper divisors (98541).

689731 is an equidigital number, since it uses as much as digits as its factorization.

689731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98540.

The product of its digits is 9072, while the sum is 34.

The square root of 689731 is about 830.5004515351. The cubic root of 689731 is about 88.3540744776.

The spelling of 689731 in words is "six hundred eighty-nine thousand, seven hundred thirty-one".