11613821561 has 2 divisors, whose sum is σ = 11613821562. Its totient is φ = 11613821560.

The previous prime is 11613821509. The next prime is 11613821587. The reversal of 11613821561 is 16512831611.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11026050025 + 587771536 = 105005^2 + 24244^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11613821561 is a prime.

It is not a weakly prime, because it can be changed into another prime (11613821501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5806910780 + 5806910781.

It is an arithmetic number, because the mean of its divisors is an integer number (5806910781).

Almost surely, 2^11613821561 is an apocalyptic number.

It is an amenable number.

11613821561 is a deficient number, since it is larger than the sum of its proper divisors (1).

11613821561 is an equidigital number, since it uses as much as digits as its factorization.

11613821561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 35.

The spelling of 11613821561 in words is "eleven billion, six hundred thirteen million, eight hundred twenty-one thousand, five hundred sixty-one".