665239919 has 4 divisors (see below), whose sum is σ = 666315240. Its totient is φ = 664164600.

The previous prime is 665239907. The next prime is 665239933. The reversal of 665239919 is 919932566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665239919 is a prime.

It is a super-2 number, since 2×665239919² = 885088299662253122, 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 (665239969) 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 3 ways as a sum of consecutive naturals, for example, 536732 + ... + 537969.

It is an arithmetic number, because the mean of its divisors is an integer number (166578810).

Almost surely, 2^665239919 is an apocalyptic number.

665239919 is a deficient number, since it is larger than the sum of its proper divisors (1075321).

665239919 is a wasteful number, since it uses less digits than its factorization.

665239919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075320.

The product of its digits is 787320, while the sum is 50.

The square root of 665239919 is about 25792.2453268419. The cubic root of 665239919 is about 872.9568301951.

The spelling of 665239919 in words is "six hundred sixty-five million, two hundred thirty-nine thousand, nine hundred nineteen".