64660420044221 has 4 divisors (see below), whose sum is σ = 64662694525500. Its totient is φ = 64658145562944.

The previous prime is 64660420044217. The next prime is 64660420044257. The reversal of 64660420044221 is 12244002406646.

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

It can be written as a sum of positive squares in 2 ways, for example, as 36189007432900 + 28471412611321 = 6015730^2 + 5335861^2 .

It is a cyclic number.

It is not a de Polignac number, because 64660420044221 - 2² = 64660420044217 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 (64660420064221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1137197996 + ... + 1137254853.

It is an arithmetic number, because the mean of its divisors is an integer number (16165673631375).

Almost surely, 2^{64660420044221} is an apocalyptic number.

It is an amenable number.

64660420044221 is a deficient number, since it is larger than the sum of its proper divisors (2274481279).

64660420044221 is a wasteful number, since it uses less digits than its factorization.

64660420044221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2274481278.

The product of its (nonzero) digits is 442368, while the sum is 41.

The spelling of 64660420044221 in words is "sixty-four trillion, six hundred sixty billion, four hundred twenty million, forty-four thousand, two hundred twenty-one".