866578559616 has 704 divisors, whose sum is σ = 3230717889600. Its totient is φ = 224934174720.

The previous prime is 866578559611. The next prime is 866578559677. The reversal of 866578559616 is 616955875668.

It is a happy number.

866578559616 is a `hidden beast` number, since 8 + 6 + 6 + 5 + 7 + 8 + 559 + 61 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (704).

It is a super-2 number, since 2×866578559616² (a number of 25 digits) contains 22 as substring.

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

Its product of digits (653184000) is a multiple of the sum of its prime divisors (1512).

It is not an unprimeable number, because it can be changed into a prime (866578559611) by changing a digit.

It is a polite number, since it can be written in 87 ways as a sum of consecutive naturals, for example, 581986200 + ... + 581987688.

Almost surely, 2^866578559616 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 866578559616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1615358944800).

866578559616 is an abundant number, since it is smaller than the sum of its proper divisors (2364139329984).

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

866578559616 is an equidigital number, since it uses as much as digits as its factorization.

866578559616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1551 (or 1512 counting only the distinct ones).

The product of its digits is 653184000, while the sum is 72.

The spelling of 866578559616 in words is "eight hundred sixty-six billion, five hundred seventy-eight million, five hundred fifty-nine thousand, six hundred sixteen".