6561853849 has 2 divisors, whose sum is σ = 6561853850. Its totient is φ = 6561853848.

The previous prime is 6561853819. The next prime is 6561853877. The reversal of 6561853849 is 9483581656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4732752025 + 1829101824 = 68795^2 + 42768^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561853849 - 2²³ = 6553465241 is a prime.

It is a super-2 number, since 2×6561853849² = 86115851871272229602, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6561853849.

It is not a weakly prime, because it can be changed into another prime (6561853819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280926924 + 3280926925.

It is an arithmetic number, because the mean of its divisors is an integer number (3280926925).

Almost surely, 2^6561853849 is an apocalyptic number.

It is an amenable number.

6561853849 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561853849 is an equidigital number, since it uses as much as digits as its factorization.

6561853849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6220800, while the sum is 55.

The square root of 6561853849 is about 81005.2705013692. The cubic root of 6561853849 is about 1872.1566479004.

The spelling of 6561853849 in words is "six billion, five hundred sixty-one million, eight hundred fifty-three thousand, eight hundred forty-nine".