6561021188 has 6 divisors (see below), whose sum is σ = 11481787086. Its totient is φ = 3280510592.

The previous prime is 6561021143. The next prime is 6561021211. The reversal of 6561021188 is 8811201656.

It can be written as a sum of positive squares in only one way, i.e., 6219215044 + 341806144 = 78862^2 + 18488^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820127645 + ... + 820127652.

It is an arithmetic number, because the mean of its divisors is an integer number (1913631181).

Almost surely, 2^6561021188 is an apocalyptic number.

It is an amenable number.

6561021188 is a deficient number, since it is larger than the sum of its proper divisors (4920765898).

6561021188 is a wasteful number, since it uses less digits than its factorization.

6561021188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1640255301 (or 1640255299 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 38.

The square root of 6561021188 is about 81000.1307900179. The cubic root of 6561021188 is about 1872.0774559625.

The spelling of 6561021188 in words is "six billion, five hundred sixty-one million, twenty-one thousand, one hundred eighty-eight".