66616665 has 8 divisors (see below), whose sum is σ = 106586688. Its totient is φ = 35528880.

The previous prime is 66616663. The next prime is 66616691. The reversal of 66616665 is 56661666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66616665 - 2¹ = 66616663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66616663) 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 7 ways as a sum of consecutive naturals, for example, 2220541 + ... + 2220570.

It is an arithmetic number, because the mean of its divisors is an integer number (13323336).

Almost surely, 2^66616665 is an apocalyptic number.

It is an amenable number.

66616665 is a deficient number, since it is larger than the sum of its proper divisors (39970023).

66616665 is a wasteful number, since it uses less digits than its factorization.

66616665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4441119.

The product of its digits is 233280, while the sum is 42.

The square root of 66616665 is about 8161.9032706839. The cubic root of 66616665 is about 405.3787342712.

The spelling of 66616665 in words is "sixty-six million, six hundred sixteen thousand, six hundred sixty-five".