646705 has 4 divisors (see below), whose sum is σ = 776052. Its totient is φ = 517360.

The previous prime is 646687. The next prime is 646721. The reversal of 646705 is 507646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 507646 = 2 ⋅253823.

It can be written as a sum of positive squares in 2 ways, for example, as 246016 + 400689 = 496^2 + 633^2 .

It is not a de Polignac number, because 646705 - 2⁷ = 646577 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64666 + ... + 64675.

It is an arithmetic number, because the mean of its divisors is an integer number (194013).

2⁶⁴⁶⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

646705 is a deficient number, since it is larger than the sum of its proper divisors (129347).

646705 is a wasteful number, since it uses less digits than its factorization.

646705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129346.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 646705 is about 804.1797062846. The cubic root of 646705 is about 86.4772903062.

The spelling of 646705 in words is "six hundred forty-six thousand, seven hundred five".