6561729576864 has 864 divisors, whose sum is σ = 24722475523200. Its totient is φ = 1603514880000.

The previous prime is 6561729576851. The next prime is 6561729576887. The reversal of 6561729576864 is 4686759271656.

6561729576864 is a `hidden beast` number, since 6 + 561 + 7 + 2 + 9 + 57 + 6 + 8 + 6 + 4 = 666.

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 = 6561729576792 and 6561729576801.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 1192822114 + ... + 1192827614.

It is an arithmetic number, because the mean of its divisors is an integer number (28613976300).

Almost surely, 2^{6561729576864} 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 6561729576864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12361237761600).

6561729576864 is an abundant number, since it is smaller than the sum of its proper divisors (18160745946336).

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

6561729576864 is a wasteful number, since it uses less digits than its factorization.

6561729576864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5722 (or 5692 counting only the distinct ones).

The product of its digits is 914457600, while the sum is 72.

The spelling of 6561729576864 in words is "six trillion, five hundred sixty-one billion, seven hundred twenty-nine million, five hundred seventy-six thousand, eight hundred sixty-four".