643717 has 4 divisors (see below), whose sum is σ = 646380. Its totient is φ = 641056.

The previous prime is 643703. The next prime is 643723. The reversal of 643717 is 717346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 25921 + 617796 = 161^2 + 786^2 .

It is a cyclic number.

It is not a de Polignac number, because 643717 - 2⁷ = 643589 is a prime.

It is a Duffinian number.

643717 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643217) 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, 928 + ... + 1465.

It is an arithmetic number, because the mean of its divisors is an integer number (161595).

2⁶⁴³⁷¹⁷ is an apocalyptic number.

It is an amenable number.

643717 is a deficient number, since it is larger than the sum of its proper divisors (2663).

643717 is a wasteful number, since it uses less digits than its factorization.

643717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2662.

The product of its digits is 3528, while the sum is 28.

The square root of 643717 is about 802.3197616911. The cubic root of 643717 is about 86.3438996954.

The spelling of 643717 in words is "six hundred forty-three thousand, seven hundred seventeen".