66333547809 has 21 divisors (see below), whose sum is σ = 99465252673. Its totient is φ = 44217729252.

The previous prime is 66333547771. The next prime is 66333547829. The reversal of 66333547809 is 90874533366.

The square root of 66333547809 is 257553.

It is a perfect power (a square), and thus also a powerful number.

66333547809 is a `hidden beast` number, since 6 + 63 + 33 + 547 + 8 + 0 + 9 = 666.

It is not a de Polignac number, because 66333547809 - 2¹³ = 66333539617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66333547829) 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 in 20 ways as a sum of consecutive naturals, for example, 6949162 + ... + 6958700.

Almost surely, 2^66333547809 is an apocalyptic number.

66333547809 is the 257553-rd square number.

66333547809 is the 128777-th centered octagonal number.

It is an amenable number.

66333547809 is a deficient number, since it is larger than the sum of its proper divisors (33131704864).

66333547809 is an frugal number, since it uses more digits than its factorization.

66333547809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19096 (or 9542 counting only the distinct ones).

The product of its (nonzero) digits is 9797760, while the sum is 54.

The spelling of 66333547809 in words is "sixty-six billion, three hundred thirty-three million, five hundred forty-seven thousand, eight hundred nine".