665282561 has 2 divisors, whose sum is σ = 665282562. Its totient is φ = 665282560.

The previous prime is 665282557. The next prime is 665282581. The reversal of 665282561 is 165282566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 639078400 + 26204161 = 25280^2 + 5119^2 .

It is a cyclic number.

It is not a de Polignac number, because 665282561 - 2² = 665282557 is a prime.

It is equal to p_34546379 and since 665282561 and 34546379 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (665282581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332641280 + 332641281.

It is an arithmetic number, because the mean of its divisors is an integer number (332641281).

Almost surely, 2^665282561 is an apocalyptic number.

It is an amenable number.

665282561 is a deficient number, since it is larger than the sum of its proper divisors (1).

665282561 is an equidigital number, since it uses as much as digits as its factorization.

665282561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 172800, while the sum is 41.

The square root of 665282561 is about 25793.0719574075. The cubic root of 665282561 is about 872.9754820272.

The spelling of 665282561 in words is "six hundred sixty-five million, two hundred eighty-two thousand, five hundred sixty-one".