21308814565 has 16 divisors (see below), whose sum is σ = 26893472256. Its totient is φ = 16185873600.

The previous prime is 21308814563. The next prime is 21308814589. The reversal of 21308814565 is 56541880312.

It is not a de Polignac number, because 21308814565 - 2¹ = 21308814563 is a prime.

It is a super-2 number, since 2×21308814565² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308814563) 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 15 ways as a sum of consecutive naturals, for example, 1288731 + ... + 1305160.

It is an arithmetic number, because the mean of its divisors is an integer number (1680842016).

Almost surely, 2^21308814565 is an apocalyptic number.

It is an amenable number.

21308814565 is a deficient number, since it is larger than the sum of its proper divisors (5584657691).

21308814565 is a wasteful number, since it uses less digits than its factorization.

21308814565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2593980.

The product of its (nonzero) digits is 230400, while the sum is 43.

The spelling of 21308814565 in words is "twenty-one billion, three hundred eight million, eight hundred fourteen thousand, five hundred sixty-five".