21716804 has 18 divisors (see below), whose sum is σ = 38416014. Its totient is φ = 10741920.

The previous prime is 21716767. The next prime is 21716809. The reversal of 21716804 is 40861712.

It can be written as a sum of positive squares in only one way, i.e., 19784704 + 1932100 = 4448^2 + 1390^2 .

It is not an unprimeable number, because it can be changed into a prime (21716809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 77144 + ... + 77424.

It is an arithmetic number, because the mean of its divisors is an integer number (2134223).

Almost surely, 2^21716804 is an apocalyptic number.

It is an amenable number.

21716804 is a deficient number, since it is larger than the sum of its proper divisors (16699210).

21716804 is a wasteful number, since it uses less digits than its factorization.

21716804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563 (or 422 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21716804 is about 4660.1291827588. The cubic root of 21716804 is about 278.9964242892.

The spelling of 21716804 in words is "twenty-one million, seven hundred sixteen thousand, eight hundred four".