665161649 has 2 divisors, whose sum is σ = 665161650. Its totient is φ = 665161648.

The previous prime is 665161631. The next prime is 665161657. The reversal of 665161649 is 946161566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 614296225 + 50865424 = 24785^2 + 7132^2 .

It is a cyclic number.

It is not a de Polignac number, because 665161649 - 2¹² = 665157553 is a prime.

It is not a weakly prime, because it can be changed into another prime (665161349) 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, 332580824 + 332580825.

It is an arithmetic number, because the mean of its divisors is an integer number (332580825).

Almost surely, 2^665161649 is an apocalyptic number.

It is an amenable number.

665161649 is a deficient number, since it is larger than the sum of its proper divisors (1).

665161649 is an equidigital number, since it uses as much as digits as its factorization.

665161649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 233280, while the sum is 44.

The square root of 665161649 is about 25790.7279656857. The cubic root of 665161649 is about 872.9225924166.

The spelling of 665161649 in words is "six hundred sixty-five million, one hundred sixty-one thousand, six hundred forty-nine".