665661611 has 8 divisors (see below), whose sum is σ = 682482240. Its totient is φ = 648951808.

The previous prime is 665661593. The next prime is 665661641. The reversal of 665661611 is 116166566.

It is a happy number.

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 665661611 - 2¹⁰ = 665660587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665661641) 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, 15476 + ... + 39633.

It is an arithmetic number, because the mean of its divisors is an integer number (85310280).

Almost surely, 2^665661611 is an apocalyptic number.

665661611 is a deficient number, since it is larger than the sum of its proper divisors (16820629).

665661611 is a wasteful number, since it uses less digits than its factorization.

665661611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55413.

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

The square root of 665661611 is about 25800.4188144301. The cubic root of 665661611 is about 873.1412454442.

The spelling of 665661611 in words is "six hundred sixty-five million, six hundred sixty-one thousand, six hundred eleven".