6561441656 has 128 divisors (see below), whose sum is σ = 16116572160. Its totient is φ = 2428272000.

The previous prime is 6561441647. The next prime is 6561441673.

6561441656 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2137835 + ... + 2140901.

It is an arithmetic number, because the mean of its divisors is an integer number (125910720).

Almost surely, 2^6561441656 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 6561441656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8058286080).

6561441656 is an abundant number, since it is smaller than the sum of its proper divisors (9555130504).

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

6561441656 is a wasteful number, since it uses less digits than its factorization.

6561441656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3265 (or 3261 counting only the distinct ones).

The product of its digits is 518400, while the sum is 44.

The square root of 6561441656 is about 81002.7262257265. The cubic root of 6561441656 is about 1872.1174462743.

The spelling of 6561441656 in words is "six billion, five hundred sixty-one million, four hundred forty-one thousand, six hundred fifty-six".