21304105 has 4 divisors (see below), whose sum is σ = 25564932. Its totient is φ = 17043280.

The previous prime is 21304097. The next prime is 21304109. The reversal of 21304105 is 50140312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6985449 + 14318656 = 2643^2 + 3784^2 .

It is not a de Polignac number, because 21304105 - 2³ = 21304097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21304109) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2130406 + ... + 2130415.

It is an arithmetic number, because the mean of its divisors is an integer number (6391233).

Almost surely, 2^21304105 is an apocalyptic number.

It is an amenable number.

21304105 is a deficient number, since it is larger than the sum of its proper divisors (4260827).

21304105 is an equidigital number, since it uses as much as digits as its factorization.

21304105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4260826.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21304105 is about 4615.6370091245. The cubic root of 21304105 is about 277.2177906356.

Adding to 21304105 its reverse (50140312), we get a palindrome (71444417).

The spelling of 21304105 in words is "twenty-one million, three hundred four thousand, one hundred five".