665128800 has 576 divisors, whose sum is σ = 2834818560. Its totient is φ = 147363840.

The previous prime is 665128787. The next prime is 665128829. The reversal of 665128800 is 8821566.

It is a happy number.

665128800 is a `hidden beast` number, since 66 + 512 + 8 + 80 + 0 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 8013559 + ... + 8013641.

It is an arithmetic number, because the mean of its divisors is an integer number (4921560).

Almost surely, 2^665128800 is an apocalyptic number.

665128800 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 665128800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1417409280).

665128800 is an abundant number, since it is smaller than the sum of its proper divisors (2169689760).

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

665128800 is a wasteful number, since it uses less digits than its factorization.

665128800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172 (or 153 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 665128800 is about 25790.0911204284. The cubic root of 665128800 is about 872.9082224228.

The spelling of 665128800 in words is "six hundred sixty-five million, one hundred twenty-eight thousand, eight hundred".