21828866 has 4 divisors (see below), whose sum is σ = 32743302. Its totient is φ = 10914432.

The previous prime is 21828847. The next prime is 21828869. The reversal of 21828866 is 66882812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11363641 + 10465225 = 3371^2 + 3235^2 .

It is not an unprimeable number, because it can be changed into a prime (21828869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5457215 + ... + 5457218.

Almost surely, 2^21828866 is an apocalyptic number.

21828866 is a deficient number, since it is larger than the sum of its proper divisors (10914436).

21828866 is a wasteful number, since it uses less digits than its factorization.

21828866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10914435.

The product of its digits is 73728, while the sum is 41.

The square root of 21828866 is about 4672.1371983280. The cubic root of 21828866 is about 279.4754891604.

The spelling of 21828866 in words is "twenty-one million, eight hundred twenty-eight thousand, eight hundred sixty-six".