66065999 has 4 divisors (see below), whose sum is σ = 66379320. Its totient is φ = 65752680.

The previous prime is 66065977. The next prime is 66066043. The reversal of 66065999 is 99956066.

It is a happy number.

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 66065999 - 2²⁰ = 65017423 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 (66061999) 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, 156344 + ... + 156765.

It is an arithmetic number, because the mean of its divisors is an integer number (16594830).

Almost surely, 2^66065999 is an apocalyptic number.

66065999 is a deficient number, since it is larger than the sum of its proper divisors (313321).

66065999 is a wasteful number, since it uses less digits than its factorization.

66065999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 313320.

The product of its (nonzero) digits is 787320, while the sum is 50.

The square root of 66065999 is about 8128.0993473259. The cubic root of 66065999 is about 404.2586631455.

The spelling of 66065999 in words is "sixty-six million, sixty-five thousand, nine hundred ninety-nine".