656161661 has 2 divisors, whose sum is σ = 656161662. Its totient is φ = 656161660.

The previous prime is 656161651. The next prime is 656161669. The reversal of 656161661 is 166161656.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 409860025 + 246301636 = 20245^2 + 15694^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-656161661 is a prime.

It is a Sophie Germain 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 (656161669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328080830 + 328080831.

It is an arithmetic number, because the mean of its divisors is an integer number (328080831).

Almost surely, 2^656161661 is an apocalyptic number.

It is an amenable number.

656161661 is a deficient number, since it is larger than the sum of its proper divisors (1).

656161661 is an equidigital number, since it uses as much as digits as its factorization.

656161661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 38.

The square root of 656161661 is about 25615.6526561398. The cubic root of 656161661 is about 868.9676666188.

The spelling of 656161661 in words is "six hundred fifty-six million, one hundred sixty-one thousand, six hundred sixty-one".