66665699 has 4 divisors (see below), whose sum is σ = 70174440. Its totient is φ = 63156960.

The previous prime is 66665657. The next prime is 66665701. The reversal of 66665699 is 99656666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99656666 = 2 ⋅49828333.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66665699 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66665699.

It is not an unprimeable number, because it can be changed into a prime (66665629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1754342 + ... + 1754379.

It is an arithmetic number, because the mean of its divisors is an integer number (17543610).

Almost surely, 2^66665699 is an apocalyptic number.

66665699 is a deficient number, since it is larger than the sum of its proper divisors (3508741).

66665699 is a wasteful number, since it uses less digits than its factorization.

66665699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3508740.

The product of its digits is 3149280, while the sum is 53.

The square root of 66665699 is about 8164.9065518229. The cubic root of 66665699 is about 405.4781711807.

The spelling of 66665699 in words is "sixty-six million, six hundred sixty-five thousand, six hundred ninety-nine".