21050513005 has 4 divisors (see below), whose sum is σ = 25260615612. Its totient is φ = 16840410400.

The previous prime is 21050512907. The next prime is 21050513047. The reversal of 21050513005 is 50031505012.

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 12008214724 + 9042298281 = 109582^2 + 95091^2 .

It is not a de Polignac number, because 21050513005 - 2²⁷ = 20916295277 is a prime.

It is a Smith number, since the sum of its digits (22) 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 a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2105051296 + ... + 2105051305.

It is an arithmetic number, because the mean of its divisors is an integer number (6315153903).

Almost surely, 2^21050513005 is an apocalyptic number.

It is an amenable number.

21050513005 is a deficient number, since it is larger than the sum of its proper divisors (4210102607).

21050513005 is an equidigital number, since it uses as much as digits as its factorization.

21050513005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4210102606.

The product of its (nonzero) digits is 750, while the sum is 22.

The spelling of 21050513005 in words is "twenty-one billion, fifty million, five hundred thirteen thousand, five".