21645704 has 16 divisors (see below), whose sum is σ = 41576220. Its totient is φ = 10558720.

The previous prime is 21645697. The next prime is 21645707. The reversal of 21645704 is 40754612.

It can be written as a sum of positive squares in 2 ways, for example, as 21141604 + 504100 = 4598^2 + 710^2 .

It is not an unprimeable number, because it can be changed into a prime (21645707) 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, 32669 + ... + 33324.

Almost surely, 2^21645704 is an apocalyptic number.

It is an amenable number.

21645704 is a deficient number, since it is larger than the sum of its proper divisors (19930516).

21645704 is a wasteful number, since it uses less digits than its factorization.

21645704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66040 (or 66036 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 21645704 is about 4652.4943847360. The cubic root of 21645704 is about 278.6916168020.

The spelling of 21645704 in words is "twenty-one million, six hundred forty-five thousand, seven hundred four".