665996958 has 64 divisors (see below), whose sum is σ = 1636761600. Its totient is φ = 199039680.

The previous prime is 665996941. The next prime is 665996971. The reversal of 665996958 is 859699566.

It is a junction number, because it is equal to n+sod(n) for n = 665996895 and 665996904.

It is a congruent 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 31 ways as a sum of consecutive naturals, for example, 35683 + ... + 51041.

It is an arithmetic number, because the mean of its divisors is an integer number (25574400).

Almost surely, 2^665996958 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665996958, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (818380800).

665996958 is an abundant number, since it is smaller than the sum of its proper divisors (970764642).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665996958 is a wasteful number, since it uses less digits than its factorization.

665996958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15454 (or 15448 counting only the distinct ones).

The product of its digits is 31492800, while the sum is 63.

The square root of 665996958 is about 25806.9168635077. The cubic root of 665996958 is about 873.2878445251.

The spelling of 665996958 in words is "six hundred sixty-five million, nine hundred ninety-six thousand, nine hundred fifty-eight".