66655361521 has 4 divisors (see below), whose sum is σ = 76177556032. Its totient is φ = 57133167012.

The previous prime is 66655361519. The next prime is 66655361561. The reversal of 66655361521 is 12516355666.

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 66655361521 - 2¹ = 66655361519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66655361501) 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, 4761097245 + ... + 4761097258.

It is an arithmetic number, because the mean of its divisors is an integer number (19044389008).

Almost surely, 2^66655361521 is an apocalyptic number.

It is an amenable number.

66655361521 is a deficient number, since it is larger than the sum of its proper divisors (9522194511).

66655361521 is an equidigital number, since it uses as much as digits as its factorization.

66655361521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9522194510.

The product of its digits is 972000, while the sum is 46.

The spelling of 66655361521 in words is "sixty-six billion, six hundred fifty-five million, three hundred sixty-one thousand, five hundred twenty-one".