9811661 has 2 divisors, whose sum is σ = 9811662. Its totient is φ = 9811660.

The previous prime is 9811643. The next prime is 9811663. The reversal of 9811661 is 1661189.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5851561 + 3960100 = 2419^2 + 1990^2 .

It is a cyclic number.

It is not a de Polignac number, because 9811661 - 2⁶ = 9811597 is a prime.

It is a Sophie Germain prime.

Together with 9811663, 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 (9811663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4905830 + 4905831.

It is an arithmetic number, because the mean of its divisors is an integer number (4905831).

Almost surely, 2^9811661 is an apocalyptic number.

It is an amenable number.

9811661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9811661 is an equidigital number, since it uses as much as digits as its factorization.

9811661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 32.

The square root of 9811661 is about 3132.3570996935. The cubic root of 9811661 is about 214.0823408643.

The spelling of 9811661 in words is "nine million, eight hundred eleven thousand, six hundred sixty-one".