66543361599 has 32 divisors (see below), whose sum is σ = 104254343424. Its totient is φ = 37220417280.

The previous prime is 66543361561. The next prime is 66543361609. The reversal of 66543361599 is 99516334566.

It is a Cunningham number, because it is equal to 257960²-1.

It is not a de Polignac number, because 66543361599 - 2¹⁶ = 66543296063 is a prime.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66543361799) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3343572 + ... + 3363414.

It is an arithmetic number, because the mean of its divisors is an integer number (3257948232).

Almost surely, 2^66543361599 is an apocalyptic number.

66543361599 is a deficient number, since it is larger than the sum of its proper divisors (37710981825).

66543361599 is a wasteful number, since it uses less digits than its factorization.

66543361599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27687.

The product of its digits is 15746400, while the sum is 57.

The spelling of 66543361599 in words is "sixty-six billion, five hundred forty-three million, three hundred sixty-one thousand, five hundred ninety-nine".