689721 has 8 divisors (see below), whose sum is σ = 926400. Its totient is φ = 456432.

The previous prime is 689713. The next prime is 689723. The reversal of 689721 is 127986.

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

It is not a de Polignac number, because 689721 - 2³ = 689713 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 689721.

It is not an unprimeable number, because it can be changed into a prime (689723) 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, 325 + ... + 1218.

It is an arithmetic number, because the mean of its divisors is an integer number (115800).

2⁶⁸⁹⁷²¹ is an apocalyptic number.

It is an amenable number.

689721 is a deficient number, since it is larger than the sum of its proper divisors (236679).

689721 is a wasteful number, since it uses less digits than its factorization.

689721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1695.

The product of its digits is 6048, while the sum is 33.

The square root of 689721 is about 830.4944310470. The cubic root of 689721 is about 88.3536474778.

The spelling of 689721 in words is "six hundred eighty-nine thousand, seven hundred twenty-one".