665506538 has 8 divisors (see below), whose sum is σ = 1001971620. Its totient is φ = 331516000.

The previous prime is 665506487. The next prime is 665506549. The reversal of 665506538 is 835605566.

It can be written as a sum of positive squares in 2 ways, for example, as 555403489 + 110103049 = 23567^2 + 10493^2 .

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

It is a Curzon number.

It is an unprimeable number.

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, 617963 + ... + 619038.

Almost surely, 2^665506538 is an apocalyptic number.

665506538 is a deficient number, since it is larger than the sum of its proper divisors (336465082).

665506538 is a wasteful number, since it uses less digits than its factorization.

665506538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237272.

The product of its (nonzero) digits is 648000, while the sum is 44.

The square root of 665506538 is about 25797.4133974707. The cubic root of 665506538 is about 873.0734376442.

The spelling of 665506538 in words is "six hundred sixty-five million, five hundred six thousand, five hundred thirty-eight".