66550009 has 2 divisors, whose sum is σ = 66550010. Its totient is φ = 66550008.

The previous prime is 66549991. The next prime is 66550021. The reversal of 66550009 is 90005566.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66373609 + 176400 = 8147^2 + 420^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66550009 is a prime.

It is not a weakly prime, because it can be changed into another prime (66550069) 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, 33275004 + 33275005.

It is an arithmetic number, because the mean of its divisors is an integer number (33275005).

Almost surely, 2^66550009 is an apocalyptic number.

It is an amenable number.

66550009 is a deficient number, since it is larger than the sum of its proper divisors (1).

66550009 is an equidigital number, since it uses as much as digits as its factorization.

66550009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 66550009 is about 8157.8188874233. The cubic root of 66550009 is about 405.2434831184.

The spelling of 66550009 in words is "sixty-six million, five hundred fifty thousand, nine".