6500006661661 has 2 divisors, whose sum is σ = 6500006661662. Its totient is φ = 6500006661660.

The previous prime is 6500006661637. The next prime is 6500006661691. The reversal of 6500006661661 is 1661666000056.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5993071205625 + 506935456036 = 2448075^2 + 711994^2 .

It is a cyclic number.

It is not a de Polignac number, because 6500006661661 - 2³⁹ = 5950250847773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6500006661691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3250003330830 + 3250003330831.

It is an arithmetic number, because the mean of its divisors is an integer number (3250003330831).

Almost surely, 2^{6500006661661} is an apocalyptic number.

It is an amenable number.

6500006661661 is a deficient number, since it is larger than the sum of its proper divisors (1).

6500006661661 is an equidigital number, since it uses as much as digits as its factorization.

6500006661661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 233280, while the sum is 43.

The spelling of 6500006661661 in words is "six trillion, five hundred billion, six million, six hundred sixty-one thousand, six hundred sixty-one".