21845872705 has 4 divisors (see below), whose sum is σ = 26215047252. Its totient is φ = 17476698160.

The previous prime is 21845872663. The next prime is 21845872739. The reversal of 21845872705 is 50727854812.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15952700416 + 5893172289 = 126304^2 + 76767^2 .

It is not a de Polignac number, because 21845872705 - 2¹⁵ = 21845839937 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2184587266 + ... + 2184587275.

It is an arithmetic number, because the mean of its divisors is an integer number (6553761813).

Almost surely, 2^21845872705 is an apocalyptic number.

It is an amenable number.

21845872705 is a deficient number, since it is larger than the sum of its proper divisors (4369174547).

21845872705 is an equidigital number, since it uses as much as digits as its factorization.

21845872705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4369174546.

The product of its (nonzero) digits is 1254400, while the sum is 49.

The spelling of 21845872705 in words is "twenty-one billion, eight hundred forty-five million, eight hundred seventy-two thousand, seven hundred five".