665865900 has 288 divisors, whose sum is σ = 2499840000. Its totient is φ = 151986240.

The previous prime is 665865883. The next prime is 665865901. The reversal of 665865900 is 9568566.

665865900 is a `hidden beast` number, since 6 + 6 + 58 + 6 + 590 + 0 = 666.

665865900 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (665865901) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 925741 + ... + 926459.

It is an arithmetic number, because the mean of its divisors is an integer number (8680000).

Almost surely, 2^665865900 is an apocalyptic number.

665865900 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665865900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1249920000).

665865900 is an abundant number, since it is smaller than the sum of its proper divisors (1833974100).

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

665865900 is a wasteful number, since it uses less digits than its factorization.

665865900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 763 (or 736 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 45.

The square root of 665865900 is about 25804.3775356043. The cubic root of 665865900 is about 873.2305575435.

The spelling of 665865900 in words is "six hundred sixty-five million, eight hundred sixty-five thousand, nine hundred".