646657 has 4 divisors (see below), whose sum is σ = 705456. Its totient is φ = 587860.

The previous prime is 646643. The next prime is 646669. The reversal of 646657 is 756646.

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 646657 - 2¹⁵ = 613889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646637) 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, 29383 + ... + 29404.

It is an arithmetic number, because the mean of its divisors is an integer number (176364).

2⁶⁴⁶⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

646657 is a deficient number, since it is larger than the sum of its proper divisors (58799).

646657 is a wasteful number, since it uses less digits than its factorization.

646657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58798.

The product of its digits is 30240, while the sum is 34.

The square root of 646657 is about 804.1498616552. The cubic root of 646657 is about 86.4751507358.

The spelling of 646657 in words is "six hundred forty-six thousand, six hundred fifty-seven".