66563521 has 2 divisors, whose sum is σ = 66563522. Its totient is φ = 66563520.

The previous prime is 66563513. The next prime is 66563531. The reversal of 66563521 is 12536566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49843600 + 16719921 = 7060^2 + 4089^2 .

It is a cyclic number.

It is not a de Polignac number, because 66563521 - 2³ = 66563513 is a prime.

It is not a weakly prime, because it can be changed into another prime (66563531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33281760 + 33281761.

It is an arithmetic number, because the mean of its divisors is an integer number (33281761).

Almost surely, 2^66563521 is an apocalyptic number.

It is an amenable number.

66563521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66563521 is an equidigital number, since it uses as much as digits as its factorization.

66563521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 34.

The square root of 66563521 is about 8158.6470079297. The cubic root of 66563521 is about 405.2709075044.

The spelling of 66563521 in words is "sixty-six million, five hundred sixty-three thousand, five hundred twenty-one".