665601 has 16 divisors (see below), whose sum is σ = 972288. Its totient is φ = 403200.

The previous prime is 665591. The next prime is 665603. The reversal of 665601 is 106566.

It is not a de Polignac number, because 665601 - 2⁵ = 665569 is a prime.

665601 is a lucky number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1371 + ... + 1791.

It is an arithmetic number, because the mean of its divisors is an integer number (60768).

It is a Proth number, since it is equal to 325 ⋅ 2¹¹ + 1 and 325 < 2¹¹.

2⁶⁶⁵⁶⁰¹ is an apocalyptic number.

It is an amenable number.

665601 is a deficient number, since it is larger than the sum of its proper divisors (306687).

665601 is a wasteful number, since it uses less digits than its factorization.

665601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 472.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 665601 is about 815.8437350375. The cubic root of 665601 is about 87.3114743705.

The spelling of 665601 in words is "six hundred sixty-five thousand, six hundred one".