865663001280 has 1344 divisors, whose sum is σ = 3969520128000. Its totient is φ = 173632757760.

The previous prime is 865663001219. The next prime is 865663001303. The reversal of 865663001280 is 82100366568.

865663001280 is a `hidden beast` number, since 8 + 6 + 5 + 6 + 630 + 0 + 1 + 2 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1344).

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

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 212222281 + ... + 212226359.

It is an arithmetic number, because the mean of its divisors is an integer number (2953512000).

Almost surely, 2^865663001280 is an apocalyptic number.

865663001280 is a gapful number since it is divisible by the number (80) 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 865663001280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1984760064000).

865663001280 is an abundant number, since it is smaller than the sum of its proper divisors (3103857126720).

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

865663001280 is a wasteful number, since it uses less digits than its factorization.

865663001280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4163 (or 4136 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 865663001280 in words is "eight hundred sixty-five billion, six hundred sixty-three million, one thousand, two hundred eighty".