865663879680 has 360 divisors, whose sum is σ = 3097947311316. Its totient is φ = 223391416320.

The previous prime is 865663879579. The next prime is 865663879699. The reversal of 865663879680 is 86978366568.

865663879680 is a `hidden beast` number, since 86 + 5 + 6 + 6 + 387 + 96 + 80 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 853864706304 + 11799173376 = 924048^2 + 108624^2 .

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 865663879599 and 865663879608.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 22121892 + ... + 22160988.

Almost surely, 2^865663879680 is an apocalyptic number.

865663879680 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 865663879680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1548973655658).

865663879680 is an abundant number, since it is smaller than the sum of its proper divisors (2232283431636).

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

865663879680 is a wasteful number, since it uses less digits than its factorization.

865663879680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39188 (or 39138 counting only the distinct ones).

The product of its (nonzero) digits is 627056640, while the sum is 72.

The spelling of 865663879680 in words is "eight hundred sixty-five billion, six hundred sixty-three million, eight hundred seventy-nine thousand, six hundred eighty".