21724084865 has 16 divisors (see below), whose sum is σ = 31545562752. Its totient is φ = 14020249344.

The previous prime is 21724084847. The next prime is 21724084897. The reversal of 21724084865 is 56848042712.

It is a cyclic number.

It is not a de Polignac number, because 21724084865 - 2⁶ = 21724084801 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 18254939 + ... + 18256128.

It is an arithmetic number, because the mean of its divisors is an integer number (1971597672).

Almost surely, 2^21724084865 is an apocalyptic number.

It is an amenable number.

21724084865 is a deficient number, since it is larger than the sum of its proper divisors (9821477887).

21724084865 is a wasteful number, since it uses less digits than its factorization.

21724084865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36511096.

The product of its (nonzero) digits is 860160, while the sum is 47.

The spelling of 21724084865 in words is "twenty-one billion, seven hundred twenty-four million, eighty-four thousand, eight hundred sixty-five".