665902649 has 2 divisors, whose sum is σ = 665902650. Its totient is φ = 665902648.

The previous prime is 665902603. The next prime is 665902663. The reversal of 665902649 is 946209566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 665898025 + 4624 = 25805^2 + 68^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665902649 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (665902849) 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, 332951324 + 332951325.

It is an arithmetic number, because the mean of its divisors is an integer number (332951325).

Almost surely, 2^665902649 is an apocalyptic number.

It is an amenable number.

665902649 is a deficient number, since it is larger than the sum of its proper divisors (1).

665902649 is an equidigital number, since it uses as much as digits as its factorization.

665902649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 699840, while the sum is 47.

The square root of 665902649 is about 25805.0895948842. The cubic root of 665902649 is about 873.2466217187.

The spelling of 665902649 in words is "six hundred sixty-five million, nine hundred two thousand, six hundred forty-nine".