66550409 has 2 divisors, whose sum is σ = 66550410. Its totient is φ = 66550408.

The previous prime is 66550399. The next prime is 66550441. The reversal of 66550409 is 90405566.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64000000 + 2550409 = 8000^2 + 1597^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66550409 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66550499) 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, 33275204 + 33275205.

It is an arithmetic number, because the mean of its divisors is an integer number (33275205).

Almost surely, 2^66550409 is an apocalyptic number.

It is an amenable number.

66550409 is a deficient number, since it is larger than the sum of its proper divisors (1).

66550409 is an equidigital number, since it uses as much as digits as its factorization.

66550409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32400, while the sum is 35.

The square root of 66550409 is about 8157.8434037434. The cubic root of 66550409 is about 405.2442950244.

The spelling of 66550409 in words is "sixty-six million, five hundred fifty thousand, four hundred nine".