21338605 has 4 divisors (see below), whose sum is σ = 25606332. Its totient is φ = 17070880.

The previous prime is 21338599. The next prime is 21338609. The reversal of 21338605 is 50683312.

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 8934121 + 12404484 = 2989^2 + 3522^2 .

It is not a de Polignac number, because 21338605 - 2⁷ = 21338477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21338609) 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, 2133856 + ... + 2133865.

It is an arithmetic number, because the mean of its divisors is an integer number (6401583).

Almost surely, 2^21338605 is an apocalyptic number.

It is an amenable number.

21338605 is a deficient number, since it is larger than the sum of its proper divisors (4267727).

21338605 is an equidigital number, since it uses as much as digits as its factorization.

21338605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4267726.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21338605 is about 4619.3727929233. The cubic root of 21338605 is about 277.3673526683.

The spelling of 21338605 in words is "twenty-one million, three hundred thirty-eight thousand, six hundred five".