27981663841 has 4 divisors (see below), whose sum is σ = 27999476784. Its totient is φ = 27963850900.

The previous prime is 27981663833. The next prime is 27981663901. The reversal of 27981663841 is 14836618972.

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 27981663841 - 2³ = 27981663833 is a prime.

It is a super-2 number, since 2×27981663841² (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 (27981660841) 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 in 3 ways as a sum of consecutive naturals, for example, 8904115 + ... + 8907256.

It is an arithmetic number, because the mean of its divisors is an integer number (6999869196).

Almost surely, 2^27981663841 is an apocalyptic number.

It is an amenable number.

27981663841 is a deficient number, since it is larger than the sum of its proper divisors (17812943).

27981663841 is a wasteful number, since it uses less digits than its factorization.

27981663841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17812942.

The product of its digits is 3483648, while the sum is 55.

The spelling of 27981663841 in words is "twenty-seven billion, nine hundred eighty-one million, six hundred sixty-three thousand, eight hundred forty-one".