66639109 has 8 divisors (see below), whose sum is σ = 69406848. Its totient is φ = 63922320.

The previous prime is 66639047. The next prime is 66639113. The reversal of 66639109 is 90193666.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66639109 - 2¹⁵ = 66606341 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 (66639149) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10057 + ... + 15310.

It is an arithmetic number, because the mean of its divisors is an integer number (8675856).

Almost surely, 2^66639109 is an apocalyptic number.

It is an amenable number.

66639109 is a deficient number, since it is larger than the sum of its proper divisors (2767739).

66639109 is a wasteful number, since it uses less digits than its factorization.

66639109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25475.

The product of its (nonzero) digits is 52488, while the sum is 40.

The square root of 66639109 is about 8163.2780793012. The cubic root of 66639109 is about 405.4242549064.

The spelling of 66639109 in words is "sixty-six million, six hundred thirty-nine thousand, one hundred nine".