9640661 has 2 divisors, whose sum is σ = 9640662. Its totient is φ = 9640660.

The previous prime is 9640639. The next prime is 9640663. The reversal of 9640661 is 1660469.

9640661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4866436 + 4774225 = 2206^2 + 2185^2 .

It is an emirp because it is prime and its reverse (1660469) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9640661 - 2¹⁸ = 9378517 is a prime.

It is a Sophie Germain prime.

Together with 9640663, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9640663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4820330 + 4820331.

It is an arithmetic number, because the mean of its divisors is an integer number (4820331).

Almost surely, 2^9640661 is an apocalyptic number.

It is an amenable number.

9640661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9640661 is an equidigital number, since it uses as much as digits as its factorization.

9640661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 9640661 is about 3104.9413843099. The cubic root of 9640661 is about 212.8313520265.

It can be divided in two parts, 9640 and 661, that added together give a palindrome (10301).

The spelling of 9640661 in words is "nine million, six hundred forty thousand, six hundred sixty-one".