21784408689 has 4 divisors (see below), whose sum is σ = 29045878256. Its totient is φ = 14522939124.

The previous prime is 21784408649. The next prime is 21784408757. The reversal of 21784408689 is 98680448712.

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 not a de Polignac number, because 21784408689 - 2¹¹ = 21784406641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21784408619) 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, 3630734779 + ... + 3630734784.

It is an arithmetic number, because the mean of its divisors is an integer number (7261469564).

Almost surely, 2^21784408689 is an apocalyptic number.

It is an amenable number.

21784408689 is a deficient number, since it is larger than the sum of its proper divisors (7261469567).

21784408689 is an equidigital number, since it uses as much as digits as its factorization.

21784408689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7261469566.

The product of its (nonzero) digits is 6193152, while the sum is 57.

The spelling of 21784408689 in words is "twenty-one billion, seven hundred eighty-four million, four hundred eight thousand, six hundred eighty-nine".