21100205 has 16 divisors (see below), whose sum is σ = 29414784. Its totient is φ = 14230080.

The previous prime is 21100193. The next prime is 21100207. The reversal of 21100205 is 50200112.

It is not a de Polignac number, because 21100205 - 2⁶ = 21100141 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100207) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2807 + ... + 7076.

It is an arithmetic number, because the mean of its divisors is an integer number (1838424).

Almost surely, 2^21100205 is an apocalyptic number.

It is an amenable number.

21100205 is a deficient number, since it is larger than the sum of its proper divisors (8314579).

21100205 is an equidigital number, since it uses as much as digits as its factorization.

21100205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9956.

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 21100205 is about 4593.4959453558. The cubic root of 21100205 is about 276.3305437290.

Adding to 21100205 its reverse (50200112), we get a palindrome (71300317).

The spelling of 21100205 in words is "twenty-one million, one hundred thousand, two hundred five".