865120856320 has 288 divisors, whose sum is σ = 2456292787200. Its totient is φ = 291741327360.

The previous prime is 865120856311. The next prime is 865120856323. The reversal of 865120856320 is 23658021568.

It is not an unprimeable number, because it can be changed into a prime (865120856323) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26765289 + ... + 26797591.

It is an arithmetic number, because the mean of its divisors is an integer number (8528794400).

Almost surely, 2^865120856320 is an apocalyptic number.

865120856320 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 865120856320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1228146393600).

865120856320 is an abundant number, since it is smaller than the sum of its proper divisors (1591171930880).

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

865120856320 is an equidigital number, since it uses as much as digits as its factorization.

865120856320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32406 (or 32378 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 46.

Adding to 865120856320 its reverse (23658021568), we get a palindrome (888778877888).

It can be divided in two parts, 865120 and 856320, that added together give a triangular number (1721440 = T₁₈₅₅).

The spelling of 865120856320 in words is "eight hundred sixty-five billion, one hundred twenty million, eight hundred fifty-six thousand, three hundred twenty".