66611665 has 8 divisors (see below), whose sum is σ = 80118720. Its totient is φ = 53166192.

The previous prime is 66611651. The next prime is 66611669. The reversal of 66611665 is 56611666.

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

It is a cyclic number.

It is not a de Polignac number, because 66611665 - 2⁷ = 66611537 is a prime.

It is a super-2 number, since 2×66611665² = 8874227828144450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66611669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12979 + ... + 17368.

It is an arithmetic number, because the mean of its divisors is an integer number (10014840).

Almost surely, 2^66611665 is an apocalyptic number.

It is an amenable number.

66611665 is a deficient number, since it is larger than the sum of its proper divisors (13507055).

66611665 is a wasteful number, since it uses less digits than its factorization.

66611665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30791.

The product of its digits is 38880, while the sum is 37.

The square root of 66611665 is about 8161.5969638301. The cubic root of 66611665 is about 405.3685919423.

Subtracting from 66611665 its reverse (56611666), we obtain a palindrome (9999999).

It can be divided in two parts, 66611 and 665, that added together give a palindrome (67276).

The spelling of 66611665 in words is "sixty-six million, six hundred eleven thousand, six hundred sixty-five".