16566656005561 has 2 divisors, whose sum is σ = 16566656005562. Its totient is φ = 16566656005560.

The previous prime is 16566656005483. The next prime is 16566656005589. The reversal of 16566656005561 is 16550065666561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15460938561600 + 1105717443961 = 3932040^2 + 1051531^2 .

It is a cyclic number.

It is not a de Polignac number, because 16566656005561 - 2⁹ = 16566656005049 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 16566656005496 and 16566656005505.

It is not a weakly prime, because it can be changed into another prime (16566656005591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8283328002780 + 8283328002781.

It is an arithmetic number, because the mean of its divisors is an integer number (8283328002781).

Almost surely, 2^{16566656005561} is an apocalyptic number.

It is an amenable number.

16566656005561 is a deficient number, since it is larger than the sum of its proper divisors (1).

16566656005561 is an equidigital number, since it uses as much as digits as its factorization.

16566656005561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29160000, while the sum is 58.

The spelling of 16566656005561 in words is "sixteen trillion, five hundred sixty-six billion, six hundred fifty-six million, five thousand, five hundred sixty-one".