656661 has 4 divisors (see below), whose sum is σ = 875552. Its totient is φ = 437772.

The previous prime is 656657. The next prime is 656671. The reversal of 656661 is 166656.

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 not a de Polignac number, because 656661 - 2² = 656657 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656651) 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, 109441 + ... + 109446.

It is an arithmetic number, because the mean of its divisors is an integer number (218888).

2⁶⁵⁶⁶⁶¹ is an apocalyptic number.

It is an amenable number.

656661 is a deficient number, since it is larger than the sum of its proper divisors (218891).

656661 is a wasteful number, since it uses less digits than its factorization.

656661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218890.

The product of its digits is 6480, while the sum is 30.

The square root of 656661 is about 810.3462223025. The cubic root of 656661 is about 86.9188038848.

The spelling of 656661 in words is "six hundred fifty-six thousand, six hundred sixty-one".