665666111 has 8 divisors (see below), whose sum is σ = 726841344. Its totient is φ = 604600920.

The previous prime is 665666077. The next prime is 665666129. The reversal of 665666111 is 111666566.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-665666111 is a prime.

It is a super-2 number, since 2×665666111² = 886222742667728642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665666171) 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, 14591 + ... + 39296.

It is an arithmetic number, because the mean of its divisors is an integer number (90855168).

Almost surely, 2^665666111 is an apocalyptic number.

665666111 is a deficient number, since it is larger than the sum of its proper divisors (61175233).

665666111 is a wasteful number, since it uses less digits than its factorization.

665666111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55021.

The product of its digits is 38880, while the sum is 38.

The square root of 665666111 is about 25800.5060221694. The cubic root of 665666111 is about 873.1432129738.

The spelling of 665666111 in words is "six hundred sixty-five million, six hundred sixty-six thousand, one hundred eleven".