66665899 has 4 divisors (see below), whose sum is σ = 67065264. Its totient is φ = 66266536.

The previous prime is 66665873. The next prime is 66665909. The reversal of 66665899 is 99856666.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66665899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66665399) 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, 199432 + ... + 199765.

It is an arithmetic number, because the mean of its divisors is an integer number (16766316).

Almost surely, 2^66665899 is an apocalyptic number.

66665899 is a deficient number, since it is larger than the sum of its proper divisors (399365).

66665899 is a wasteful number, since it uses less digits than its factorization.

66665899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399364.

The product of its digits is 4199040, while the sum is 55.

The square root of 66665899 is about 8164.9187993513. The cubic root of 66665899 is about 405.4785766643.

The spelling of 66665899 in words is "sixty-six million, six hundred sixty-five thousand, eight hundred ninety-nine".