66278609 has 4 divisors (see below), whose sum is σ = 67820016. Its totient is φ = 64737204.

The previous prime is 66278603. The next prime is 66278623. The reversal of 66278609 is 90687266.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66278609 - 2⁸ = 66278353 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66278609.

It is not an unprimeable number, because it can be changed into a prime (66278603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 770639 + ... + 770724.

It is an arithmetic number, because the mean of its divisors is an integer number (16955004).

Almost surely, 2^66278609 is an apocalyptic number.

It is an amenable number.

66278609 is a deficient number, since it is larger than the sum of its proper divisors (1541407).

66278609 is a wasteful number, since it uses less digits than its factorization.

66278609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1541406.

The product of its (nonzero) digits is 217728, while the sum is 44.

The square root of 66278609 is about 8141.1675452603. The cubic root of 66278609 is about 404.6918531923.

The spelling of 66278609 in words is "sixty-six million, two hundred seventy-eight thousand, six hundred nine".