656221 has 2 divisors, whose sum is σ = 656222. Its totient is φ = 656220.

The previous prime is 656171. The next prime is 656237. The reversal of 656221 is 122656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 656100 + 121 = 810^2 + 11^2 .

It is a cyclic number.

It is not a de Polignac number, because 656221 - 2¹³ = 648029 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 656192 and 656201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328110 + 328111.

It is an arithmetic number, because the mean of its divisors is an integer number (328111).

2⁶⁵⁶²²¹ is an apocalyptic number.

It is an amenable number.

656221 is a deficient number, since it is larger than the sum of its proper divisors (1).

656221 is an equidigital number, since it uses as much as digits as its factorization.

656221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 22.

The square root of 656221 is about 810.0746879146. The cubic root of 656221 is about 86.8993860427.

Adding to 656221 its reverse (122656), we get a palindrome (778877).

The spelling of 656221 in words is "six hundred fifty-six thousand, two hundred twenty-one".