6561940491656 has 64 divisors (see below), whose sum is σ = 13610939328000. Its totient is φ = 2940975912960.

The previous prime is 6561940491637. The next prime is 6561940491671.

6561940491656 is nontrivially palindromic in base 10.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 867305 + ... + 3725063.

It is an arithmetic number, because the mean of its divisors is an integer number (212670927000).

Almost surely, 2^{6561940491656} 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 6561940491656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6805469664000).

6561940491656 is an abundant number, since it is smaller than the sum of its proper divisors (7048998836344).

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

6561940491656 is a wasteful number, since it uses less digits than its factorization.

6561940491656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2858142 (or 2858138 counting only the distinct ones).

The product of its (nonzero) digits is 41990400, while the sum is 62.

The spelling of 6561940491656 in words is "six trillion, five hundred sixty-one billion, nine hundred forty million, four hundred ninety-one thousand, six hundred fifty-six".