2105665561 has 2 divisors, whose sum is σ = 2105665562. Its totient is φ = 2105665560.

The previous prime is 2105665537. The next prime is 2105665589. The reversal of 2105665561 is 1655665012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1722250000 + 383415561 = 41500^2 + 19581^2 .

It is a cyclic number.

It is not a de Polignac number, because 2105665561 - 2¹⁷ = 2105534489 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2105665561.

It is not a weakly prime, because it can be changed into another prime (2105665501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1052832780 + 1052832781.

It is an arithmetic number, because the mean of its divisors is an integer number (1052832781).

Almost surely, 2^2105665561 is an apocalyptic number.

It is an amenable number.

2105665561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2105665561 is an equidigital number, since it uses as much as digits as its factorization.

2105665561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54000, while the sum is 37.

The square root of 2105665561 is about 45887.5316507654. The cubic root of 2105665561 is about 1281.7297498397.

The spelling of 2105665561 in words is "two billion, one hundred five million, six hundred sixty-five thousand, five hundred sixty-one".