66193909 has 4 divisors (see below), whose sum is σ = 66231340. Its totient is φ = 66156480.

The previous prime is 66193901. The next prime is 66193913. The reversal of 66193909 is 90939166.

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 28922884 + 37271025 = 5378^2 + 6105^2 .

It is a cyclic number.

It is not a de Polignac number, because 66193909 - 2³ = 66193901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66193901) 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, 15924 + ... + 19645.

It is an arithmetic number, because the mean of its divisors is an integer number (16557835).

Almost surely, 2^66193909 is an apocalyptic number.

It is an amenable number.

66193909 is a deficient number, since it is larger than the sum of its proper divisors (37431).

66193909 is a wasteful number, since it uses less digits than its factorization.

66193909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37430.

The product of its (nonzero) digits is 78732, while the sum is 43.

The square root of 66193909 is about 8135.9639256821. The cubic root of 66193909 is about 404.5193892439.

The spelling of 66193909 in words is "sixty-six million, one hundred ninety-three thousand, nine hundred nine".