39665 has 4 divisors (see below), whose sum is σ = 47604. Its totient is φ = 31728.

The previous prime is 39659. The next prime is 39667. The reversal of 39665 is 56693.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12769 + 26896 = 113^2 + 164^2 .

It is a cyclic number.

It is not a de Polignac number, because 39665 - 2⁸ = 39409 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (39667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3962 + ... + 3971.

It is an arithmetic number, because the mean of its divisors is an integer number (11901).

2³⁹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

39665 is a deficient number, since it is larger than the sum of its proper divisors (7939).

39665 is an equidigital number, since it uses as much as digits as its factorization.

39665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7938.

The product of its digits is 4860, while the sum is 29.

The square root of 39665 is about 199.1607391029. The cubic root of 39665 is about 34.1037774988.

The spelling of 39665 in words is "thirty-nine thousand, six hundred sixty-five".