665243181 has 12 divisors (see below), whose sum is σ = 1011481120. Its totient is φ = 420153480.

The previous prime is 665243177. The next prime is 665243213. The reversal of 665243181 is 181342566.

It is a happy number.

It is not a de Polignac number, because 665243181 - 2² = 665243177 is a prime.

It is a super-2 number, since 2×665243181² = 885096979733997522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665243171) 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 11 ways as a sum of consecutive naturals, for example, 1944985 + ... + 1945326.

Almost surely, 2^665243181 is an apocalyptic number.

It is an amenable number.

665243181 is a deficient number, since it is larger than the sum of its proper divisors (346237939).

665243181 is a wasteful number, since it uses less digits than its factorization.

665243181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3890336 (or 3890333 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 665243181 is about 25792.3085628255. The cubic root of 665243181 is about 872.9582570390.

The spelling of 665243181 in words is "six hundred sixty-five million, two hundred forty-three thousand, one hundred eighty-one".