721718 has 8 divisors (see below), whose sum is σ = 1146312. Its totient is φ = 339616.

The previous prime is 721709. The next prime is 721733. The reversal of 721718 is 817127.

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

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721718.

It is an unprimeable number.

721718 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10580 + ... + 10647.

It is an arithmetic number, because the mean of its divisors is an integer number (143289).

2⁷²¹⁷¹⁸ is an apocalyptic number.

721718 is a deficient number, since it is larger than the sum of its proper divisors (424594).

721718 is a wasteful number, since it uses less digits than its factorization.

721718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21246.

The product of its digits is 784, while the sum is 26.

The square root of 721718 is about 849.5398754620. The cubic root of 721718 is about 89.6993258373.

The spelling of 721718 in words is "seven hundred twenty-one thousand, seven hundred eighteen".