6561331656 has 64 divisors (see below), whose sum is σ = 18378204480. Its totient is φ = 1934542080.

The previous prime is 6561331643. The next prime is 6561331657.

6561331656 is nontrivially palindromic in base 10.

It is not an unprimeable number, because it can be changed into a prime (6561331657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 326091 + ... + 345626.

It is an arithmetic number, because the mean of its divisors is an integer number (287159445).

Almost surely, 2^6561331656 is an apocalyptic number.

6561331656 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

6561331656 is an abundant number, since it is smaller than the sum of its proper divisors (11816872824).

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

6561331656 is a wasteful number, since it uses less digits than its factorization.

6561331656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671774 (or 671770 counting only the distinct ones).

The product of its digits is 291600, while the sum is 42.

The square root of 6561331656 is about 81002.0472333879. The cubic root of 6561331656 is about 1872.1069844439.

The spelling of 6561331656 in words is "six billion, five hundred sixty-one million, three hundred thirty-one thousand, six hundred fifty-six".