21005000005 has 32 divisors (see below), whose sum is σ = 28610444160. Its totient is φ = 14664142080.

The previous prime is 21004999979. The next prime is 21005000047. The reversal of 21005000005 is 50000050012.

It is not a de Polignac number, because 21005000005 - 2⁵ = 21004999973 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 237874 + ... + 313996.

It is an arithmetic number, because the mean of its divisors is an integer number (894076380).

Almost surely, 2^21005000005 is an apocalyptic number.

It is an amenable number.

21005000005 is a deficient number, since it is larger than the sum of its proper divisors (7605444155).

21005000005 is a wasteful number, since it uses less digits than its factorization.

21005000005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76341.

The product of its (nonzero) digits is 50, while the sum is 13.

Adding to 21005000005 its reverse (50000050012), we get a palindrome (71005050017).

The spelling of 21005000005 in words is "twenty-one billion, five million, five", and thus it is an aban number and an uban number.