20345317661 has 2 divisors, whose sum is σ = 20345317662. Its totient is φ = 20345317660.

The previous prime is 20345317637. The next prime is 20345317673. The reversal of 20345317661 is 16671354302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15816835225 + 4528482436 = 125765^2 + 67294^2 .

It is a cyclic number.

It is not a de Polignac number, because 20345317661 - 2¹⁰ = 20345316637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20345317961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10172658830 + 10172658831.

It is an arithmetic number, because the mean of its divisors is an integer number (10172658831).

Almost surely, 2^20345317661 is an apocalyptic number.

It is an amenable number.

20345317661 is a deficient number, since it is larger than the sum of its proper divisors (1).

20345317661 is an equidigital number, since it uses as much as digits as its factorization.

20345317661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 90720, while the sum is 38.

The spelling of 20345317661 in words is "twenty billion, three hundred forty-five million, three hundred seventeen thousand, six hundred sixty-one".