665678876549 has 2 divisors, whose sum is σ = 665678876550. Its totient is φ = 665678876548.

The previous prime is 665678876537. The next prime is 665678876587. The reversal of 665678876549 is 945678876566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 479685063649 + 185993812900 = 692593^2 + 431270^2 .

It is a cyclic number.

It is not a de Polignac number, because 665678876549 - 2⁸ = 665678876293 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 665678876549.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665678876249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332839438274 + 332839438275.

It is an arithmetic number, because the mean of its divisors is an integer number (332839438275).

Almost surely, 2^665678876549 is an apocalyptic number.

It is an amenable number.

665678876549 is a deficient number, since it is larger than the sum of its proper divisors (1).

665678876549 is an equidigital number, since it uses as much as digits as its factorization.

665678876549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3657830400, while the sum is 77.

The spelling of 665678876549 in words is "six hundred sixty-five billion, six hundred seventy-eight million, eight hundred seventy-six thousand, five hundred forty-nine".