665899136 has 64 divisors (see below), whose sum is σ = 1522150080. Its totient is φ = 284249088.

The previous prime is 665899133. The next prime is 665899141. The reversal of 665899136 is 631998566.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (665899133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 246851 + ... + 249533.

It is an arithmetic number, because the mean of its divisors is an integer number (23783595).

Almost surely, 2^665899136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665899136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (761075040).

665899136 is an abundant number, since it is smaller than the sum of its proper divisors (856250944).

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

665899136 is a wasteful number, since it uses less digits than its factorization.

665899136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2981 (or 2969 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 53.

The square root of 665899136 is about 25805.0215268269. The cubic root of 665899136 is about 873.2450860984.

The spelling of 665899136 in words is "six hundred sixty-five million, eight hundred ninety-nine thousand, one hundred thirty-six".