11567761721 has 2 divisors, whose sum is σ = 11567761722. Its totient is φ = 11567761720.

The previous prime is 11567761649. The next prime is 11567761757. The reversal of 11567761721 is 12716776511.

11567761721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9873204496 + 1694557225 = 99364^2 + 41165^2 .

It is a cyclic number.

It is not a de Polignac number, because 11567761721 - 2¹⁴ = 11567745337 is a prime.

It is a super-2 number, since 2×11567761721² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (11567761421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5783880860 + 5783880861.

It is an arithmetic number, because the mean of its divisors is an integer number (5783880861).

Almost surely, 2^11567761721 is an apocalyptic number.

It is an amenable number.

11567761721 is a deficient number, since it is larger than the sum of its proper divisors (1).

11567761721 is an equidigital number, since it uses as much as digits as its factorization.

11567761721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 123480, while the sum is 44.

The spelling of 11567761721 in words is "eleven billion, five hundred sixty-seven million, seven hundred sixty-one thousand, seven hundred twenty-one".