27927787681 has 4 divisors (see below), whose sum is σ = 27928595632. Its totient is φ = 27926979732.

The previous prime is 27927787639. The next prime is 27927787691. The reversal of 27927787681 is 18678772972.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 27927787681 - 2⁹ = 27927787169 is a prime.

It is a super-2 number, since 2×27927787681² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27927787631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 349695 + ... + 422068.

It is an arithmetic number, because the mean of its divisors is an integer number (6982148908).

Almost surely, 2^27927787681 is an apocalyptic number.

It is an amenable number.

27927787681 is a deficient number, since it is larger than the sum of its proper divisors (807951).

27927787681 is an equidigital number, since it uses as much as digits as its factorization.

27927787681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 807950.

The product of its digits is 33191424, while the sum is 64.

The spelling of 27927787681 in words is "twenty-seven billion, nine hundred twenty-seven million, seven hundred eighty-seven thousand, six hundred eighty-one".