21099205 has 8 divisors (see below), whose sum is σ = 25344000. Its totient is φ = 16862736.

The previous prime is 21099187. The next prime is 21099277. The reversal of 21099205 is 50299012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21099205 - 2⁷ = 21099077 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7596 + ... + 9994.

It is an arithmetic number, because the mean of its divisors is an integer number (3168000).

Almost surely, 2^21099205 is an apocalyptic number.

It is an amenable number.

21099205 is a deficient number, since it is larger than the sum of its proper divisors (4244795).

21099205 is a wasteful number, since it uses less digits than its factorization.

21099205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4163.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 21099205 is about 4593.3870945088. The cubic root of 21099205 is about 276.3261782910.

The spelling of 21099205 in words is "twenty-one million, ninety-nine thousand, two hundred five".