66165639 has 4 divisors (see below), whose sum is σ = 88220856. Its totient is φ = 44110424.

The previous prime is 66165637. The next prime is 66165643. The reversal of 66165639 is 93656166.

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

It is a cyclic number.

It is not a de Polignac number, because 66165639 - 2¹ = 66165637 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66165639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66165637) 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, 11027604 + ... + 11027609.

It is an arithmetic number, because the mean of its divisors is an integer number (22055214).

Almost surely, 2^66165639 is an apocalyptic number.

66165639 is a deficient number, since it is larger than the sum of its proper divisors (22055217).

66165639 is a wasteful number, since it uses less digits than its factorization.

66165639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22055216.

The product of its digits is 174960, while the sum is 42.

The square root of 66165639 is about 8134.2263922269. The cubic root of 66165639 is about 404.4617938564.

The spelling of 66165639 in words is "sixty-six million, one hundred sixty-five thousand, six hundred thirty-nine".