721717 has 4 divisors (see below), whose sum is σ = 753120. Its totient is φ = 690316.

The previous prime is 721709. The next prime is 721733. The reversal of 721717 is 717127.

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.

It is a cyclic number.

It is not a de Polignac number, because 721717 - 2³ = 721709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721691 and 721700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15667 + ... + 15712.

It is an arithmetic number, because the mean of its divisors is an integer number (188280).

2⁷²¹⁷¹⁷ is an apocalyptic number.

It is an amenable number.

721717 is a deficient number, since it is larger than the sum of its proper divisors (31403).

721717 is a wasteful number, since it uses less digits than its factorization.

721717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31402.

The product of its digits is 686, while the sum is 25.

The square root of 721717 is about 849.5392869079. The cubic root of 721717 is about 89.6992844086.

The spelling of 721717 in words is "seven hundred twenty-one thousand, seven hundred seventeen", and thus it is an iban number.