27811212561 has 12 divisors (see below), whose sum is σ = 43823729040. Its totient is φ = 16855280280.

The previous prime is 27811212557. The next prime is 27811212587. The reversal of 27811212561 is 16521211872.

It is a happy number.

27811212561 is a `hidden beast` number, since 2 + 7 + 81 + 1 + 2 + 12 + 561 = 666.

It is not a de Polignac number, because 27811212561 - 2² = 27811212557 is a prime.

It is a super-2 number, since 2×27811212561² (a number of 22 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (27811212511) 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 in 11 ways as a sum of consecutive naturals, for example, 140460571 + ... + 140460768.

It is an arithmetic number, because the mean of its divisors is an integer number (3651977420).

Almost surely, 2^27811212561 is an apocalyptic number.

It is an amenable number.

27811212561 is a deficient number, since it is larger than the sum of its proper divisors (16012516479).

27811212561 is a wasteful number, since it uses less digits than its factorization.

27811212561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280921356 (or 280921353 counting only the distinct ones).

The product of its digits is 13440, while the sum is 36.

The spelling of 27811212561 in words is "twenty-seven billion, eight hundred eleven million, two hundred twelve thousand, five hundred sixty-one".