656647 has 4 divisors (see below), whose sum is σ = 679320. Its totient is φ = 633976.

The previous prime is 656609. The next prime is 656651. The reversal of 656647 is 746656.

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

It is a cyclic number.

It is not a de Polignac number, because 656647 - 2⁷ = 656519 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 (656657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11293 + ... + 11350.

It is an arithmetic number, because the mean of its divisors is an integer number (169830).

2⁶⁵⁶⁶⁴⁷ is an apocalyptic number.

656647 is a deficient number, since it is larger than the sum of its proper divisors (22673).

656647 is a wasteful number, since it uses less digits than its factorization.

656647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22672.

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

The square root of 656647 is about 810.3375839735. The cubic root of 656647 is about 86.9181861780.

Subtracting 656647 from its reverse (746656), we obtain a palindrome (90009).

The spelling of 656647 in words is "six hundred fifty-six thousand, six hundred forty-seven".