66440064221 has 4 divisors (see below), whose sum is σ = 66442339392. Its totient is φ = 66437789052.

The previous prime is 66440064199. The next prime is 66440064247. The reversal of 66440064221 is 12246004466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66440064221 - 2³⁰ = 65366322397 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 (66440064421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093205 + ... + 1152378.

It is an arithmetic number, because the mean of its divisors is an integer number (16610584848).

Almost surely, 2^66440064221 is an apocalyptic number.

It is an amenable number.

66440064221 is a deficient number, since it is larger than the sum of its proper divisors (2275171).

66440064221 is a wasteful number, since it uses less digits than its factorization.

66440064221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2275170.

The product of its (nonzero) digits is 55296, while the sum is 35.

Adding to 66440064221 its reverse (12246004466), we get a palindrome (78686068687).

The spelling of 66440064221 in words is "sixty-six billion, four hundred forty million, sixty-four thousand, two hundred twenty-one".