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665 = 5719
BaseRepresentation
bin1010011001
3220122
422121
510130
63025
71640
oct1231
9818
10665
11555
12475
133c2
14357
152e5
hex299

665 has 8 divisors (see below), whose sum is σ = 960. Its totient is φ = 432.

The previous prime is 661. The next prime is 673. The reversal of 665 is 566.

Subtracting from 665 its reverse (566), we obtain a palindrome (99).

It is a happy number.

665 is nontrivially palindromic in base 9 and base 11.

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

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 665 - 22 = 661 is a prime.

It is a magnanimous number.

665 is an undulating number in base 9.

665 is a nontrivial repdigit in base 11.

It is a plaindrome in base 11, base 14 and base 16.

It is a nialpdrome in base 10 and base 11.

It is a zygodrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (661) 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 7 ways as a sum of consecutive naturals, for example, 26 + ... + 44.

It is an arithmetic number, because the mean of its divisors is an integer number (120).

It is an amenable number.

665 is a deficient number, since it is larger than the sum of its proper divisors (295).

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

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

The sum of its prime factors is 31.

The product of its digits is 180, while the sum is 17.

The square root of 665 is about 25.7875939165. The cubic root of 665 is about 8.7285187352.

The spelling of 665 in words is "six hundred sixty-five", and thus it is an aban number and an oban number.

Divisors: 1 5 7 19 35 95 133 665