16561565011 has 2 divisors, whose sum is σ = 16561565012. Its totient is φ = 16561565010.

The previous prime is 16561565003. The next prime is 16561565017. The reversal of 16561565011 is 11056516561.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 16561565011 - 2³ = 16561565003 is a prime.

It is a super-4 number, since 4×16561565011⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (16561565017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8280782505 + 8280782506.

It is an arithmetic number, because the mean of its divisors is an integer number (8280782506).

Almost surely, 2^16561565011 is an apocalyptic number.

16561565011 is a deficient number, since it is larger than the sum of its proper divisors (1).

16561565011 is an equidigital number, since it uses as much as digits as its factorization.

16561565011 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27000, while the sum is 37.

The spelling of 16561565011 in words is "sixteen billion, five hundred sixty-one million, five hundred sixty-five thousand, eleven".