6561881653 has 2 divisors, whose sum is σ = 6561881654. Its totient is φ = 6561881652.

The previous prime is 6561881639. The next prime is 6561881659. The reversal of 6561881653 is 3561881656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5226856209 + 1335025444 = 72297^2 + 36538^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561881653 - 2⁵ = 6561881621 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6561881597 and 6561881606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6561881659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280940826 + 3280940827.

It is an arithmetic number, because the mean of its divisors is an integer number (3280940827).

Almost surely, 2^6561881653 is an apocalyptic number.

It is an amenable number.

6561881653 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561881653 is an equidigital number, since it uses as much as digits as its factorization.

6561881653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1036800, while the sum is 49.

The square root of 6561881653 is about 81005.4421196502. The cubic root of 6561881653 is about 1872.1592921415.

The spelling of 6561881653 in words is "six billion, five hundred sixty-one million, eight hundred eighty-one thousand, six hundred fifty-three".