665549 has 2 divisors, whose sum is σ = 665550. Its totient is φ = 665548.

The previous prime is 665527. The next prime is 665557. The reversal of 665549 is 945566.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 422500 + 243049 = 650^2 + 493^2 .

It is a cyclic number.

It is not a de Polignac number, because 665549 - 2⁸ = 665293 is a prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332774 + 332775.

It is an arithmetic number, because the mean of its divisors is an integer number (332775).

2⁶⁶⁵⁵⁴⁹ is an apocalyptic number.

It is an amenable number.

665549 is a deficient number, since it is larger than the sum of its proper divisors (1).

665549 is an equidigital number, since it uses as much as digits as its factorization.

665549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 35.

The square root of 665549 is about 815.8118655671. The cubic root of 665549 is about 87.3092005784.

It can be divided in two parts, 665 and 549, that multiplied together give a triangular number (365085 = T₈₅₄).

The spelling of 665549 in words is "six hundred sixty-five thousand, five hundred forty-nine".