66643563221 has 16 divisors (see below), whose sum is σ = 74441894400. Its totient is φ = 59367364848.

The previous prime is 66643563199. The next prime is 66643563223. The reversal of 66643563221 is 12236534666.

It is a de Polignac number, because none of the positive numbers 2^k-66643563221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66643563223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1266611 + ... + 1318176.

It is an arithmetic number, because the mean of its divisors is an integer number (4652618400).

Almost surely, 2^66643563221 is an apocalyptic number.

It is an amenable number.

66643563221 is a deficient number, since it is larger than the sum of its proper divisors (7798331179).

66643563221 is a wasteful number, since it uses less digits than its factorization.

66643563221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2584888.

The product of its digits is 933120, while the sum is 44.

The spelling of 66643563221 in words is "sixty-six billion, six hundred forty-three million, five hundred sixty-three thousand, two hundred twenty-one".