66845309 has 4 divisors (see below), whose sum is σ = 70777404. Its totient is φ = 62913216.

The previous prime is 66845299. The next prime is 66845321. The reversal of 66845309 is 90354866.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 54804409 + 12040900 = 7403^2 + 3470^2 .

It is a cyclic number.

It is not a de Polignac number, because 66845309 - 2²⁰ = 65796733 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66845369) 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, 1966022 + ... + 1966055.

It is an arithmetic number, because the mean of its divisors is an integer number (17694351).

Almost surely, 2^66845309 is an apocalyptic number.

It is an amenable number.

66845309 is a deficient number, since it is larger than the sum of its proper divisors (3932095).

66845309 is a wasteful number, since it uses less digits than its factorization.

66845309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3932094.

The product of its (nonzero) digits is 155520, while the sum is 41.

The square root of 66845309 is about 8175.8980546482. The cubic root of 66845309 is about 405.8419896014.

The spelling of 66845309 in words is "sixty-six million, eight hundred forty-five thousand, three hundred nine".