66511672634521 has 2 divisors, whose sum is σ = 66511672634522. Its totient is φ = 66511672634520.

The previous prime is 66511672634501. The next prime is 66511672634569. The reversal of 66511672634521 is 12543627611566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41146952038921 + 25364720595600 = 6414589^2 + 5036340^2 .

It is a cyclic number.

It is not a de Polignac number, because 66511672634521 - 2⁹ = 66511672634009 is a prime.

It is not a weakly prime, because it can be changed into another prime (66511672634501) 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 as a sum of consecutive naturals, namely, 33255836317260 + 33255836317261.

It is an arithmetic number, because the mean of its divisors is an integer number (33255836317261).

Almost surely, 2^{66511672634521} is an apocalyptic number.

It is an amenable number.

66511672634521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66511672634521 is an equidigital number, since it uses as much as digits as its factorization.

66511672634521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10886400, while the sum is 55.

The spelling of 66511672634521 in words is "sixty-six trillion, five hundred eleven billion, six hundred seventy-two million, six hundred thirty-four thousand, five hundred twenty-one".