656609 has 2 divisors, whose sum is σ = 656610. Its totient is φ = 656608.

The previous prime is 656603. The next prime is 656651. The reversal of 656609 is 906656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 409600 + 247009 = 640^2 + 497^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-656609 is a prime.

It is a super-2 number, since 2×656609² = 862270757762, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656603) 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 as a sum of consecutive naturals, namely, 328304 + 328305.

It is an arithmetic number, because the mean of its divisors is an integer number (328305).

2⁶⁵⁶⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

656609 is a deficient number, since it is larger than the sum of its proper divisors (1).

656609 is an equidigital number, since it uses as much as digits as its factorization.

656609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 656609 is about 810.3141366162. The cubic root of 656609 is about 86.9165095010.

Subtracting 656609 from its reverse (906656), we obtain a cube (250047 = 63³).

The spelling of 656609 in words is "six hundred fifty-six thousand, six hundred nine".