21210071205 has 32 divisors (see below), whose sum is σ = 34354938240. Its totient is φ = 11172972800.

The previous prime is 21210071189. The next prime is 21210071227. The reversal of 21210071205 is 50217001212.

It is not a de Polignac number, because 21210071205 - 2⁴ = 21210071189 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, 618079 + ... + 651491.

It is an arithmetic number, because the mean of its divisors is an integer number (1073591820).

Almost surely, 2^21210071205 is an apocalyptic number.

It is an amenable number.

21210071205 is a deficient number, since it is larger than the sum of its proper divisors (13144867035).

21210071205 is a wasteful number, since it uses less digits than its factorization.

21210071205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33941.

The product of its (nonzero) digits is 280, while the sum is 21.

Adding to 21210071205 its reverse (50217001212), we get a palindrome (71427072417).

It can be divided in two parts, 2121007 and 1205, that added together give a palindrome (2122212).

The spelling of 21210071205 in words is "twenty-one billion, two hundred ten million, seventy-one thousand, two hundred five".