21207704 has 32 divisors (see below), whose sum is σ = 48120480. Its totient is φ = 8553984.

The previous prime is 21207673. The next prime is 21207707. The reversal of 21207704 is 40770212.

It is a self number, because there is not a number n which added to its sum of digits gives 21207704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21207707) 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 7 ways as a sum of consecutive naturals, for example, 10187 + ... + 12090.

It is an arithmetic number, because the mean of its divisors is an integer number (1503765).

Almost surely, 2^21207704 is an apocalyptic number.

It is an amenable number.

21207704 is an abundant number, since it is smaller than the sum of its proper divisors (26912776).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21207704 is a wasteful number, since it uses less digits than its factorization.

21207704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22307 (or 22303 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 23.

The square root of 21207704 is about 4605.1822982375. The cubic root of 21207704 is about 276.7990218483.

Adding to 21207704 its reverse (40770212), we get a palindrome (61977916).

The spelling of 21207704 in words is "twenty-one million, two hundred seven thousand, seven hundred four".