6640965 has 24 divisors (see below), whose sum is σ = 12189528. Its totient is φ = 3333120.

The previous prime is 6640939. The next prime is 6640967. The reversal of 6640965 is 5690466.

It is a happy number.

6640965 is a `hidden beast` number, since 6 + 640 + 9 + 6 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 2405601 + 4235364 = 1551^2 + 2058^2 .

It is not a de Polignac number, because 6640965 - 2⁶ = 6640901 is a prime.

It is a super-2 number, since 2×6640965² = 88204832262450, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3576 + ... + 5105.

It is an arithmetic number, because the mean of its divisors is an integer number (507897).

Almost surely, 2^6640965 is an apocalyptic number.

It is an amenable number.

6640965 is a deficient number, since it is larger than the sum of its proper divisors (5548563).

6640965 is a wasteful number, since it uses less digits than its factorization.

6640965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8709 (or 8706 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 6640965 is about 2577.0069848567. The cubic root of 6640965 is about 187.9650323527.

Subtracting from 6640965 its sum of digits (36), we obtain a square (6640929 = 2577²).

The spelling of 6640965 in words is "six million, six hundred forty thousand, nine hundred sixty-five".