21728822 has 8 divisors (see below), whose sum is σ = 34510536. Its totient is φ = 10225312.

The previous prime is 21728809. The next prime is 21728827. The reversal of 21728822 is 22882712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21728827) 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 3 ways as a sum of consecutive naturals, for example, 319508 + ... + 319575.

It is an arithmetic number, because the mean of its divisors is an integer number (4313817).

Almost surely, 2^21728822 is an apocalyptic number.

21728822 is a deficient number, since it is larger than the sum of its proper divisors (12781714).

21728822 is a wasteful number, since it uses less digits than its factorization.

21728822 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639102.

The product of its digits is 7168, while the sum is 32.

The square root of 21728822 is about 4661.4184536469. The cubic root of 21728822 is about 279.0478799993.

The spelling of 21728822 in words is "twenty-one million, seven hundred twenty-eight thousand, eight hundred twenty-two".