21043510505 has 8 divisors (see below), whose sum is σ = 25257102792. Its totient is φ = 16831548288.

The previous prime is 21043510459. The next prime is 21043510603. The reversal of 21043510505 is 50501534012.

It can be written as a sum of positive squares in 4 ways, for example, as 35617024 + 21007893481 = 5968^2 + 144941^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21043510505 - 2¹⁰ = 21043509481 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 378932 + ... + 430901.

It is an arithmetic number, because the mean of its divisors is an integer number (3157137849).

Almost surely, 2^21043510505 is an apocalyptic number.

It is an amenable number.

21043510505 is a deficient number, since it is larger than the sum of its proper divisors (4213592287).

21043510505 is an equidigital number, since it uses as much as digits as its factorization.

21043510505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 815035.

The product of its (nonzero) digits is 3000, while the sum is 26.

The spelling of 21043510505 in words is "twenty-one billion, forty-three million, five hundred ten thousand, five hundred five".