66516559 has 2 divisors, whose sum is σ = 66516560. Its totient is φ = 66516558.

The previous prime is 66516547. The next prime is 66516581. The reversal of 66516559 is 95561566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66516559 - 2¹⁹ = 65992271 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66516509) 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 as a sum of consecutive naturals, namely, 33258279 + 33258280.

It is an arithmetic number, because the mean of its divisors is an integer number (33258280).

Almost surely, 2^66516559 is an apocalyptic number.

66516559 is a deficient number, since it is larger than the sum of its proper divisors (1).

66516559 is an equidigital number, since it uses as much as digits as its factorization.

66516559 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 243000, while the sum is 43.

The square root of 66516559 is about 8155.7684493860. The cubic root of 66516559 is about 405.1755759587.

The spelling of 66516559 in words is "sixty-six million, five hundred sixteen thousand, five hundred fifty-nine".