21002100205 has 16 divisors (see below), whose sum is σ = 27145926720. Its totient is φ = 15547206528.

The previous prime is 21002100199. The next prime is 21002100221. The reversal of 21002100205 is 50200120012.

It is a cyclic number.

It is not a de Polignac number, because 21002100205 - 2¹¹ = 21002098157 is a prime.

It is a super-2 number, since 2×21002100205² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2566552 + ... + 2574721.

It is an arithmetic number, because the mean of its divisors is an integer number (1696620420).

Almost surely, 2^21002100205 is an apocalyptic number.

It is an amenable number.

21002100205 is a deficient number, since it is larger than the sum of its proper divisors (6143826515).

21002100205 is a wasteful number, since it uses less digits than its factorization.

21002100205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5141340.

The product of its (nonzero) digits is 40, while the sum is 13.

Adding to 21002100205 its reverse (50200120012), we get a palindrome (71202220217).

The spelling of 21002100205 in words is "twenty-one billion, two million, one hundred thousand, two hundred five".