665615549 has 2 divisors, whose sum is σ = 665615550. Its totient is φ = 665615548.

The previous prime is 665615507. The next prime is 665615593. The reversal of 665615549 is 945516566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 549902500 + 115713049 = 23450^2 + 10757^2 .

It is a cyclic number.

It is not a de Polignac number, because 665615549 - 2¹⁶ = 665550013 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665615449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332807774 + 332807775.

It is an arithmetic number, because the mean of its divisors is an integer number (332807775).

Almost surely, 2^665615549 is an apocalyptic number.

It is an amenable number.

665615549 is a deficient number, since it is larger than the sum of its proper divisors (1).

665615549 is an equidigital number, since it uses as much as digits as its factorization.

665615549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972000, while the sum is 47.

The square root of 665615549 is about 25799.5261390592. The cubic root of 665615549 is about 873.1211053014.

The spelling of 665615549 in words is "six hundred sixty-five million, six hundred fifteen thousand, five hundred forty-nine".