646693 has 4 divisors (see below), whose sum is σ = 662508. Its totient is φ = 630880.

The previous prime is 646687. The next prime is 646721. The reversal of 646693 is 396646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 396646 = 2 ⋅198323.

It can be written as a sum of positive squares in 2 ways, for example, as 174724 + 471969 = 418^2 + 687^2 .

It is a cyclic number.

It is not a de Polignac number, because 646693 - 2⁹ = 646181 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646643) by changing a digit.

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, 7846 + ... + 7927.

It is an arithmetic number, because the mean of its divisors is an integer number (165627).

2⁶⁴⁶⁶⁹³ is an apocalyptic number.

It is an amenable number.

646693 is a deficient number, since it is larger than the sum of its proper divisors (15815).

646693 is a wasteful number, since it uses less digits than its factorization.

646693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15814.

The product of its digits is 23328, while the sum is 34.

The square root of 646693 is about 804.1722452311. The cubic root of 646693 is about 86.4767554235.

Subtracting from 646693 its reverse (396646), we obtain a cube (250047 = 63³).

The spelling of 646693 in words is "six hundred forty-six thousand, six hundred ninety-three".