66686699 has 4 divisors (see below), whose sum is σ = 70609464. Its totient is φ = 62763936.

The previous prime is 66686693. The next prime is 66686707. The reversal of 66686699 is 99668666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99668666 = 2 ⋅49834333.

It is a cyclic number.

It is not a de Polignac number, because 66686699 - 2⁸ = 66686443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66686693) 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, 1961357 + ... + 1961390.

It is an arithmetic number, because the mean of its divisors is an integer number (17652366).

Almost surely, 2^66686699 is an apocalyptic number.

66686699 is a deficient number, since it is larger than the sum of its proper divisors (3922765).

66686699 is a wasteful number, since it uses less digits than its factorization.

66686699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3922764.

The product of its digits is 5038848, while the sum is 56.

The square root of 66686699 is about 8166.1924420136. The cubic root of 66686699 is about 405.5207425369.

The spelling of 66686699 in words is "sixty-six million, six hundred eighty-six thousand, six hundred ninety-nine".