21044310505 has 4 divisors (see below), whose sum is σ = 25253172612. Its totient is φ = 16835448400.

The previous prime is 21044310487. The next prime is 21044310509. The reversal of 21044310505 is 50501344012.

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 13047122176 + 7997188329 = 114224^2 + 89427^2 .

It is not a de Polignac number, because 21044310505 - 2⁵ = 21044310473 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21044310505.

It is not an unprimeable number, because it can be changed into a prime (21044310509) 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, 2104431046 + ... + 2104431055.

It is an arithmetic number, because the mean of its divisors is an integer number (6313293153).

Almost surely, 2^21044310505 is an apocalyptic number.

It is an amenable number.

21044310505 is a deficient number, since it is larger than the sum of its proper divisors (4208862107).

21044310505 is an equidigital number, since it uses as much as digits as its factorization.

21044310505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4208862106.

The product of its (nonzero) digits is 2400, while the sum is 25.

Adding to 21044310505 its reverse (50501344012), we get a palindrome (71545654517).

The spelling of 21044310505 in words is "twenty-one billion, forty-four million, three hundred ten thousand, five hundred five".