21704065 has 16 divisors (see below), whose sum is σ = 27532800. Its totient is φ = 16391232.

The previous prime is 21704029. The next prime is 21704069. The reversal of 21704065 is 56040712.

It is a cyclic number.

It is not a de Polignac number, because 21704065 - 2¹⁵ = 21671297 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21704069) 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 15 ways as a sum of consecutive naturals, for example, 7891 + ... + 10279.

It is an arithmetic number, because the mean of its divisors is an integer number (1720800).

Almost surely, 2^21704065 is an apocalyptic number.

It is an amenable number.

21704065 is a deficient number, since it is larger than the sum of its proper divisors (5828735).

21704065 is a wasteful number, since it uses less digits than its factorization.

21704065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2496.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21704065 is about 4658.7621746554. The cubic root of 21704065 is about 278.9418608488.

Adding to 21704065 its reverse (56040712), we get a palindrome (77744777).

The spelling of 21704065 in words is "twenty-one million, seven hundred four thousand, sixty-five".