21728016 has 30 divisors (see below), whose sum is σ = 60808670. Its totient is φ = 7242624.

The previous prime is 21728011. The next prime is 21728041. The reversal of 21728016 is 61082712.

It can be written as a sum of positive squares in only one way, i.e., 15968016 + 5760000 = 3996^2 + 2400^2 .

It is not an unprimeable number, because it can be changed into a prime (21728011) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 75301 + ... + 75588.

Almost surely, 2^21728016 is an apocalyptic number.

It is an amenable number.

21728016 is an abundant number, since it is smaller than the sum of its proper divisors (39080654).

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

21728016 is a wasteful number, since it uses less digits than its factorization.

21728016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150903 (or 150894 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21728016 is about 4661.3319984743. The cubic root of 21728016 is about 279.0444296608.

The spelling of 21728016 in words is "twenty-one million, seven hundred twenty-eight thousand, sixteen".