66644844667 has 4 divisors (see below), whose sum is σ = 66647619520. Its totient is φ = 66642069816.

The previous prime is 66644844569. The next prime is 66644844743. The reversal of 66644844667 is 76644844666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66644844667 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66644841667) 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 3 ways as a sum of consecutive naturals, for example, 1351083 + ... + 1399540.

It is an arithmetic number, because the mean of its divisors is an integer number (16661904880).

Almost surely, 2^66644844667 is an apocalyptic number.

66644844667 is a deficient number, since it is larger than the sum of its proper divisors (2774853).

66644844667 is a wasteful number, since it uses less digits than its factorization.

66644844667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2774852.

The product of its digits is 111476736, while the sum is 61.

Subtracting 66644844667 from its reverse (76644844666), we obtain a palindrome (9999999999).

The spelling of 66644844667 in words is "sixty-six billion, six hundred forty-four million, eight hundred forty-four thousand, six hundred sixty-seven".