665611331 has 16 divisors (see below), whose sum is σ = 839185920. Its totient is φ = 512825280.

The previous prime is 665611301. The next prime is 665611351. The reversal of 665611331 is 133116566.

665611331 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-665611331 is a prime.

It is a super-2 number, since 2×665611331² = 886076887911183122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665611301) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41711 + ... + 55416.

It is an arithmetic number, because the mean of its divisors is an integer number (52449120).

Almost surely, 2^665611331 is an apocalyptic number.

665611331 is a deficient number, since it is larger than the sum of its proper divisors (173574589).

665611331 is a wasteful number, since it uses less digits than its factorization.

665611331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97234.

The product of its digits is 9720, while the sum is 32.

The square root of 665611331 is about 25799.4443932423. Note that the first 3 decimals coincide. The cubic root of 665611331 is about 873.1192609772.

Adding to 665611331 its reverse (133116566), we get a palindrome (798727897).

The spelling of 665611331 in words is "six hundred sixty-five million, six hundred eleven thousand, three hundred thirty-one".