21344905 has 4 divisors (see below), whose sum is σ = 25613892. Its totient is φ = 17075920.

The previous prime is 21344903. The next prime is 21344929. The reversal of 21344905 is 50944312.

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 16867449 + 4477456 = 4107^2 + 2116^2 .

It is not a de Polignac number, because 21344905 - 2¹ = 21344903 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21344903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2134486 + ... + 2134495.

It is an arithmetic number, because the mean of its divisors is an integer number (6403473).

Almost surely, 2^21344905 is an apocalyptic number.

It is an amenable number.

21344905 is a deficient number, since it is larger than the sum of its proper divisors (4268987).

21344905 is an equidigital number, since it uses as much as digits as its factorization.

21344905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4268986.

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

The square root of 21344905 is about 4620.0546533564. The cubic root of 21344905 is about 277.3946465859.

The spelling of 21344905 in words is "twenty-one million, three hundred forty-four thousand, nine hundred five".