9665640 has 48 divisors (see below), whose sum is σ = 31414500. Its totient is φ = 2577408.

The previous prime is 9665609. The next prime is 9665641. The reversal of 9665640 is 465669.

It is a happy number.

9665640 is a `hidden beast` number, since 9 + 6 + 6 + 5 + 640 = 666.

9665640 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 9326916 + 338724 = 3054^2 + 582^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 9665595 and 9665604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9665641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13065 + ... + 13784.

Almost surely, 2^9665640 is an apocalyptic number.

9665640 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

9665640 is an abundant number, since it is smaller than the sum of its proper divisors (21748860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9665640 is a wasteful number, since it uses less digits than its factorization.

9665640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26866 (or 26859 counting only the distinct ones).

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

The square root of 9665640 is about 3108.9612413152. The cubic root of 9665640 is about 213.0150091916.

The spelling of 9665640 in words is "nine million, six hundred sixty-five thousand, six hundred forty".