21118889247 has 4 divisors (see below), whose sum is σ = 28158519000. Its totient is φ = 14079259496.

The previous prime is 21118889203. The next prime is 21118889257. The reversal of 21118889247 is 74298881112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21118889247 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21118889247.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21118889257) 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 3 ways as a sum of consecutive naturals, for example, 3519814872 + ... + 3519814877.

It is an arithmetic number, because the mean of its divisors is an integer number (7039629750).

Almost surely, 2^21118889247 is an apocalyptic number.

21118889247 is a deficient number, since it is larger than the sum of its proper divisors (7039629753).

21118889247 is an equidigital number, since it uses as much as digits as its factorization.

21118889247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7039629752.

The product of its digits is 516096, while the sum is 51.

The spelling of 21118889247 in words is "twenty-one billion, one hundred eighteen million, eight hundred eighty-nine thousand, two hundred forty-seven".