16561055511 has 96 divisors (see below), whose sum is σ = 32598978048. Its totient is φ = 7822552320.

The previous prime is 16561055453. The next prime is 16561055521. The reversal of 16561055511 is 11555016561.

It is a happy number.

It is not a de Polignac number, because 16561055511 - 2²⁹ = 16024184599 is a prime.

It is a super-2 number, since 2×16561055511² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16561055521) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 589885 + ... + 617321.

It is an arithmetic number, because the mean of its divisors is an integer number (339572688).

Almost surely, 2^16561055511 is an apocalyptic number.

16561055511 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

16561055511 is a deficient number, since it is larger than the sum of its proper divisors (16037922537).

16561055511 is a wasteful number, since it uses less digits than its factorization.

16561055511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27541 (or 27538 counting only the distinct ones).

The product of its (nonzero) digits is 22500, while the sum is 36.

The spelling of 16561055511 in words is "sixteen billion, five hundred sixty-one million, fifty-five thousand, five hundred eleven".