11009956561 has 2 divisors, whose sum is σ = 11009956562. Its totient is φ = 11009956560.

The previous prime is 11009956513. The next prime is 11009956603. The reversal of 11009956561 is 16565990011.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11007996561 + 1960000 = 104919^2 + 1400^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11009956561 is a prime.

It is not a weakly prime, because it can be changed into another prime (11009956501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5504978280 + 5504978281.

It is an arithmetic number, because the mean of its divisors is an integer number (5504978281).

Almost surely, 2^11009956561 is an apocalyptic number.

It is an amenable number.

11009956561 is a deficient number, since it is larger than the sum of its proper divisors (1).

11009956561 is an equidigital number, since it uses as much as digits as its factorization.

11009956561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72900, while the sum is 43.

The spelling of 11009956561 in words is "eleven billion, nine million, nine hundred fifty-six thousand, five hundred sixty-one".