646605 has 12 divisors (see below), whose sum is σ = 1120860. Its totient is φ = 344832.

The previous prime is 646577. The next prime is 646609. The reversal of 646605 is 506646.

It can be written as a sum of positive squares in 2 ways, for example, as 311364 + 335241 = 558^2 + 579^2 .

It is not a de Polignac number, because 646605 - 2⁵ = 646573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7140 + ... + 7229.

It is an arithmetic number, because the mean of its divisors is an integer number (93405).

2⁶⁴⁶⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

646605 is a deficient number, since it is larger than the sum of its proper divisors (474255).

646605 is a wasteful number, since it uses less digits than its factorization.

646605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14380 (or 14377 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 646605 is about 804.1175287233. The cubic root of 646605 is about 86.4728327483.

The spelling of 646605 in words is "six hundred forty-six thousand, six hundred five".