665541 has 12 divisors (see below), whose sum is σ = 975468. Its totient is φ = 437184.

The previous prime is 665527. The next prime is 665549. The reversal of 665541 is 145566.

It is a happy number.

665541 is a `hidden beast` number, since 6 + 655 + 4 + 1 = 666.

665541 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 125316 + 540225 = 354^2 + 735^2 .

It is not a de Polignac number, because 665541 - 2⁹ = 665029 is a prime.

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665549) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 151 + ... + 1163.

It is an arithmetic number, because the mean of its divisors is an integer number (81289).

2⁶⁶⁵⁵⁴¹ is an apocalyptic number.

It is an amenable number.

665541 is a deficient number, since it is larger than the sum of its proper divisors (309927).

665541 is a wasteful number, since it uses less digits than its factorization.

665541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092 (or 1089 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 665541 is about 815.8069624611. The cubic root of 665541 is about 87.3088507538.

The spelling of 665541 in words is "six hundred sixty-five thousand, five hundred forty-one".