660704221 has 2 divisors, whose sum is σ = 660704222. Its totient is φ = 660704220.

The previous prime is 660704207. The next prime is 660704249. The reversal of 660704221 is 122407066.

It is an a-pointer prime, because the next prime (660704249) can be obtained adding 660704221 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 652802500 + 7901721 = 25550^2 + 2811^2 .

It is a cyclic number.

It is not a de Polignac number, because 660704221 - 2⁵ = 660704189 is a prime.

It is a Chen prime.

It is equal to p_34320880 and since 660704221 and 34320880 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 660704221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (660704251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330352110 + 330352111.

It is an arithmetic number, because the mean of its divisors is an integer number (330352111).

Almost surely, 2^660704221 is an apocalyptic number.

It is an amenable number.

660704221 is a deficient number, since it is larger than the sum of its proper divisors (1).

660704221 is an equidigital number, since it uses as much as digits as its factorization.

660704221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 660704221 is about 25704.1673858540. The cubic root of 660704221 is about 870.9683237870.

The spelling of 660704221 in words is "six hundred sixty million, seven hundred four thousand, two hundred twenty-one".