66561550016567 has 2 divisors, whose sum is σ = 66561550016568. Its totient is φ = 66561550016566.

The previous prime is 66561550016561. The next prime is 66561550016609. The reversal of 66561550016567 is 76561005516566.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66561550016567 - 2¹⁸ = 66561549754423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66561550016561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33280775008283 + 33280775008284.

It is an arithmetic number, because the mean of its divisors is an integer number (33280775008284).

Almost surely, 2^{66561550016567} is an apocalyptic number.

66561550016567 is a deficient number, since it is larger than the sum of its proper divisors (1).

66561550016567 is an equidigital number, since it uses as much as digits as its factorization.

66561550016567 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34020000, while the sum is 59.

The spelling of 66561550016567 in words is "sixty-six trillion, five hundred sixty-one billion, five hundred fifty million, sixteen thousand, five hundred sixty-seven".