665091 has 48 divisors (see below), whose sum is σ = 1257984. Its totient is φ = 342144.

The previous prime is 665089. The next prime is 665111. The reversal of 665091 is 190566.

665091 is a `hidden beast` number, since 6 + 650 + 9 + 1 = 666.

It is not a de Polignac number, because 665091 - 2¹ = 665089 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

665091 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (665011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 28906 + ... + 28928.

It is an arithmetic number, because the mean of its divisors is an integer number (26208).

2⁶⁶⁵⁰⁹¹ is an apocalyptic number.

665091 is a deficient number, since it is larger than the sum of its proper divisors (592893).

665091 is a wasteful number, since it uses less digits than its factorization.

665091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62 (or 50 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 665091 is about 815.5311152862. The cubic root of 665091 is about 87.2891685999.

The spelling of 665091 in words is "six hundred sixty-five thousand, ninety-one".